Local fields are few are far between- Here are a few:

Cache 4302630420170620 4379 wtjxq0

Playland is a airsoft and lasertag field in Cotati, ca. Check out their facebook and website PLAYLAND707.com. They have 5 stars on yelp and it has been a great field. they do birthdays and walk on play.
Cache 4303760420170620 4379 1qpnm3
Paintball Jungle is one of the only true woodsball courses in the area. Located in American Canyon outside Vallejo. 31st is an associated store so you may bring our paint there to play in their huge wooded field or on the speedball courts!
Cache 4304230420170620 4543 nv9wem
Davis paintball offers large outdoor fields and a great playng experience
Midway paintball has several outdoor fields and is open on the weekends 4901 Midway Road Vacaville, CA 95688 (707) 399-9400