Sorry for the terse reply.
Here’s the thing: Sausilito is perfect for you: you can walk around to a bunch of nice, quaint places and keep the car in the garage. Your calf muscles will bulge after six months of those hills.
But you will need to sell a kidney to afford it. Mill Valley the same, without as many nice walking options.
Farther north, you get the rest of Marin County, which is exemplified by places like Corte Madera, which is pleasant and friendly but walking everywhere isn’t really possible. Buy a bike, maybe.
Petaluma has its moments.
But ultimately, I think if you live in the city and work in Novato, there will come a point when you’re sitting in traffic on 101 and you say to yourself, “You know, Novato isn’t so bad. I could be working in my woodshop right now instead of developing this boil on my ass.”
I was in a hurry and condensed all that to, “Novato is nice.” Sorry.