Unassuming and spare from the outside, Gate 5 house is a study in maximizing minimal space. This houseboat is part of the Dwell magazine-sponsored Marin Homes tour taking place April 30 and May 1. CNET takes you inside this and three other interesting homes now.

SAUSALITO, Calif.--Here in Marin, a county forward-thinking enough that it commissioned a world-class civic center by Frank Lloyd Wright, it should come as no surprise that many homes are truly stunning and would be envied the world over.

And the envy will probably be especially strong for those who fork over $150 to visit 10 multimillion dollar masterpieces throughout Marin, just across the Golden Gate Bridge from San Francisco, on April 30 and May 1. Dwell magazine, in conjunction with Marin magazine, is hosting the Home Tours. But as part of my Road Trip at Home series, I got a chance to visit four of the residences before the tours take place.

The four homes I toured provided a terrific cross-section of the best Marin has to offer: a Tiburon hilltop cacophony of windows featuring world-beating views of Marin, the Golden Gate Bridge, San Francisco, and Berkeley and Oakland' a spare but impressive floating home in the middle of one of Sausalito's best houseboat communities' a "Bridge House" that imaginatively spans a small valley and a river below' and a home at the top of a hill in a tree-studded and quiet neighborhood that emphasizes the beauty and grandeur of the outdoors throughout its modern interior.

As the home tour's official brochure puts it, these houses are "pushing residential architecture forward in Marin County... Discover the houses that are bringing the outdoors in, realizing dreams, and defining what modern design means."

Gate 5 House For years, one of my favorite things to do in Sausalito has been to go walking on the houseboat docks. And while there are several of them clustered together in a small area on the north end of town, I've long favored one specific dock for its quiet, the lush plants that residents grow outside, the many cats that wander peacefully along the wooden planks, and the whimsical art found up and down the dock.

So I was very happy when I discovered that the one houseboat included in the home tour is not only on my favorite dock, but is located right at my favorite part of the dock.

This is owner-architect David Spurgeon's Gate 5 House. Unassuming from the outside, inside it's a study in maximizing minimal space. After all, this is a house with two wide-open floors and no other rooms, save for a couple of bathrooms and a closet-cum-bunk-bed. Yet it features a fantastic gourmet kitchen, views to die for of Southern Marin's Richardson Bay, a boat of its own that allows Spurgeon to set sail for just about anywhere he wants to go, and much more.

Spurgeon, who works in Sausalito as an architect, started out by buying the aging tugboat that previously filled his slip and turning it over to the local fire department, which in turn moved it nearby and used it to set test fires. Once the slip was empty, Spurgeon began building his new home by hand in 2002, completing it three years later. "I built everything you see," he told me proudly.

The house is designed to be comfortable in all seasons. When it's warm, Spurgeon can open the wide doors that lead from the main upstairs space to a deck that looks out over the water. When it's cold, he keeps the doors closed, trapping heat inside. Spurgeon touts the house's green credentials: it has radiant heat in the floors, and bamboo flooring, low-E glass, steel siding, and manufactured lumber from new-growth wood.

The house also uses space wisely. In the lower level, Spurgeon installed closets that open both into his bedroom area and into the bunk bed room. The bunk is built on top of the closet, which is located at floor level. I thought using the closet would require stooping down, but that wasn't the case.

In the bathroom, Spurgeon displays more creative use of materials. For his fixtures here, he employed food service equipment, including a kettle caddy for the main plumbing. It feels industrial, but looks just right.

I asked Spurgeon something I've always wanted to know about the houseboats: Don't they suffer from mold, since they're smack dab in the middle of an extremely wet environment The only corrosive he worries about, he said, is the salt from the bay water that can attack the wood and metal of the boat.

But it doesn't look like he has much trouble with that, and when I asked him if he likes living here, he glowed. "Basically, you never really lose the connection to the outside," Spurgeon said, touting the seals that show up outside from time to time and the "pelicans that come in like marauding bombers" about 6 inches off the surface of the water. "It's an absolute cacophony of stuff with all the doors open... I love it here. I always feel like I'm camping out."

And if camping means cooking in a gourmet kitchen, sign me up.

The Bridge House Another stop on the tour was a totally unique home a bit further west in Marin: architect Stanley Saitowitz's Bridge House.

Designed for a lawyer-technologist couple that bought the property in 2002, Saitowitz saw a small gorgeous, green, lush valley with a river flowing through it and decided that rather than excavating and flattening out the space like other designers wanted to do, he'd simply bridge the gap.

Stanley Saitowitz&39's Bridge House, built over five-and-a-half years from 2002 to 2008, uses Cor-Ten cladding to give it a look of &34'a rusty machine in the landscape.&34'

"He walked out here in his tasseled loafers and drew us a picture of this building and its expanse," said Rebecca, the home's owner, who asked that her last name not be used, "and it was pretty much love at first sketch."

The house is long and fairly narrow, and gets amazing light. It has two floors--the top one has side-to-side and floor-to-ceiling windows facing east, and the lower one has windows facing west. "The whole house is sited in such a way that the sun arcs directly over the house and we don't get (much) direct sunlight," Rebecca said. "I love it because the shades are always open and I feel in touch with what's going on outside."

Indeed, the house is, as Rebecca said, a very industrial form that's been placed into an extremely natural landscape. The area is quiet, with little more sound than the burbling of the creek under the house and the rustling of the grass in the wind. And the house, with its rusted Cor-Ten cladding, fits right in to the color scheme of the little valley.

Though she was a litigator in a past life, these days she's mainly a stay-at-home mom. "Since we moved in, I've enjoyed pretty much every day," she said. "I don't go out much. I love having people come over" to play in the pool and look out at the wildlife.

One theme characterizing the house is floating. The structure itself floats above the little valley, and throughout the building are floating features, like a fireplace that Saitowitz built so the family could have both a stairway where they wanted it and an adjacent fireplace. Once he found the floating motif, Saitowitz continued with it, adding a floating barbeque, entertainment console, and buffet in different rooms. "For a big, heavy, ponderous house," Rebecca said, "it's incredibly light."

Tiburon Residence If you know anything about Marin, you know that one of the wealthiest communities here is Tiburon. Located a stone's throw--and a quick ferry ride--from San Francisco, it offers most residents incredible views of the city, the Golden Gate Bridge, and the vast amounts of green space Marin boasts.

This is the Tiburon Residence, designed by architect Ron Sutton. Located high above Richardson Bay, the house has stunning views of San Francisco, the Golden Gate Bridge, Angel Island, Oakland, and more.

But if you took all those attributes and combined them into one building, it might be the Tiburon Residence, which architect Ron Sutton designed for former Sun Microsystems engineer Bernard Lacroute and his wife.

Situated atop one of the most striking of all the hills in Tiburon, the house was built in 2008 to replace a 1960s-era ranch house that Sutton said didn't seem to take particularly good advantage of the oh-my-god views the property affords.

To maximize the space, Sutton came up with a concept to excavate the property in order to build two levels, the top of which is the living space. And what a space. From just about every room there are world-class views, with the Golden Gate Bridge dominating the vistas on the lawn, in the living room, and in the kitchen.

Sutton explained that the house is divided into two separate areas--a living space in the front, and a set of bedrooms in the back. A long, light-filled hallway and reflecting pool break up the two spaces.

Like the Bridge House and the Gate 5 House, the Tiburon Residence emphasizes bringing the gorgeous outdoors inside, and wherever you are in the home, you can see lush hills or the bay down below. San Francisco is off in the distance, an urban counterpoint to the seeming solitude at the top of this hill.

It can be extremely windy up here. But often, it's calm and warm. So Sutton designed the front of the house to feature wide doors that can be opened when the wind is quiet and shut when it's howling. But because the owners were clear that being outside was important to them, there is a sheltered back patio area that lets them take in the fresh air no matter how the wind's blowing.

And what keeps the building solid Throughout, Sutton used Texas limestone as his building blocks, a material that is at once solid, graceful, and down to earth.

For now, the owners still see signs of outside civilization in the form of a house below them and a new property being constructed just above them. But smart use of vegetation will soon block out the neighbors, and perhaps even a power line that Sutton said he tried to get a neighbor to bury to remove it from the owners' view. But he said the woman wouldn't pay the $10,000 cost of doing so, so it mars an otherwise all-natural view.

Pfau House Like the other three houses I saw, owner-architect Peter Pfau's house atop a hill in San Anselmo, Calif. about 25 minutes northwest of San Francisco, is built around the idea of enjoying the outdoors while inside.

This is the Pfau House, designed and owned by architect Peter Pfau.

In 2008, Pfau and his wife decided to remodel the 1950s-era house that stood atop this hill for decades, but when they did, they chose to maintain the character of the original building--and its relationship with the surrounding nature.

This, Pfau said, is a classic California house, in that there is a strong relationship between the building and the landscape, and indeed, most of the rooms in the house are dominated by the views of the many oaks on the property and nearby. Also, when working on the remodel, Pfau chose to use steel beams that were "pegged to the color of the oak trees," and said that "for us, it's about what does it mean to live in California How can a house be about the climate"

The question, he said, is how the couple could live outdoors even as they reside indoors. And that was just the problem he tackled when designing the remodel. And it works. The house is a big "L," with bright, wide rooms and big windows that make it feel as though the exterior landscape is part of what's in the rooms.

As well, the Ashlar Masonry walls--the original stone from the house that was here since the 1950s--help make this feel like a natural compromise between old and new, outside and inside. Pfau calls this a "dialogue between the exterior and the interior."

And like Spurgeon, Pfau harks back to that most ancient of pastimes. "Really, it's elegant camping," Pfau said.