Along 101 there's definitely a lot of strip malls behind a row of tress - that's basically what Corte Madera and parts of Strawberry are. However, 35% of Marin is preserved open space, and that doesn't include the Marin Agricultural Land Trust - where farmers in (generally North and West) Marin agree to preserve the farm land in exchange for immediate payments to make improvements to their farms.

There's a unique history in Marin surrounding open space and conservation, including the Marincello development and the actual creation of "national recreation areas." If you're interested, I'd encourage you to check out "Rebels With a Cause" ... there really is something special in Marin on this issue. http://rebelsdocumentary.org

That said, I totally agree that SF needs more density :)