Sigh, Flakey Cream in Healdsburg used to make very good donuts. But since the ownership change a couple years ago, they're not quite the same. French donuts available on Fridays. You can also get a fried dough thingie at Bovolo, here's my post,
Willi's Seafood used to have fried-to-order donuts on the dessert menu, worth checking into.