Sounds like fun but some comments. I would suggest you research some new places not just list the ones you know. There are way better examples of almost every thing you list.
Examples: Fosters Freeze is truly a dreadful chain with horrible food. In Santa Rosa one might choose Five Guys or In and Out or Phyllis Giant Burger, or Carmen's Burger Bar, or Jacksons for hamburgers.
Or Mexican, El Salvadorean, Thai, etc.
Cloverdale. The Hamburger Ranch is truly mediocre.
Ukiah The Broiler Steah House is mediocre. In Santa Rosa Starks would be better. Monty's Rotisserie would be far better.
Petaluma- A suggestion Pete' s Henny penny. better burgers, breakfasts, etc than anything you have listed. Also check out Mikes at the Yard for hot dogs.
Willits- Al's is a bad restaurant.
There are great restaurants all through California. While I would argue that the most distinctive regional food to be found here is not burgers, or hot dogs, or pizza, but California cuisine, Asian, Mexican, fusion, etc. there are certainly much better examples of food you seem to choose to be found, Explore!
Places I'd like to nominate:
Hayward-Banchero's-Italian-(little known obscure FACTOID: the East Bay at one point was "US HWY 101-E") - dinner...
Berkeley-Top Dog-Near UC Berkeley (Go Bears !!!)
Santa Rosa-Fosters Freeze-soft cones dipped in chocolate-burgers
Cloverdale-Hamburger Ranch-BBQ & Pasta...
Cloverdale-Pick's Rootbeer-rootbeer & lunch...
Ukiah - The Broiler Steakhouse-American-dinner after 4:oo PM
Willits-Al's Redwood Room-American & Thai-lunch-dinner...
Phillipsville-Riverwood Inn-lunch?-Mexican dinner-music
Samoa-(Eureka area)-Samoa Cookhouse-genuine loggers cookhouse-lunch-dinner...quirky in that there are only 1 or 2 menu items per day...call ahead for menu any particular day...
What other places would folks like to nominate...???