When I was in Vacaville one summer they were having a huge chili cookoff. http://www.downtownvacaville.com/calendar/events/rib_chili_cook_off1/
PS don't pick up hitch-hikers!
Otherwise if you can make it up to Sacramento, Biba's is amazing fancy Italian food, and Squeeze in has great cheeseburgers with that giant cheddar crisp like on the homepage today.
Are you looking for recommendations all the way down to SanDiego? Are you taking the 5 or the 1/101 ?