What route are you taking through CA?
mendocino county (off the 101):
http://www.willitsskatepark.com/MUST HIT park for sure. The place is amazing and almost always empty. Plus, at the time of year you are going for, you can buy an ounce of weed there for like a dollar.
around the santa rosa area, both right off the 101, these parks are fucking classic:
http://www.sk8parklist.com/ca_pet.htmlhttp://skatepark.com/skateparks/Santa+Rosa/CA/Santa+Rosa+Skate+Park/979SF:
http://www.iskatehere.com/spot/9but really, just skate all of SF. Don't worry about famous spots, go out to neighborhoods like the sunset and just cruise down the hills through residential areas. I swear, even if you know where the famous spots are, they aren't as fun as the house spots on the hills. If you aren't super hill skater man, its ok, because there are some very mellow downhill areas that you can just slowly make your way down with just enough speed to not have to push. If you need to go to a famous spot, this one has history and has become hot again lately and is right in the hills:
http://maps.google.com/maps?q=lincoln+high+school+San+Francisco&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&sa=N&hl=en&tab=wlits a good starting point.
You mentioned skateparks, so here are some more along the way to hit:
Oakland, right near the bay bridge:
http://www.concretedisciples.com/skateparksdb/skateparks_display.php?id=2532East bay has a bunch, none are sticking out to me. If somebody tries to take you to Dublin, punch him in the face for trying to fuck your trip up. Its bad, not even fun bad, just bad.
San Jose area has way too many for me to list, just google it yourself. The super big one requires full pads and money to skate it, so don't go there. Only losers wear pads. This is a fact.
Off the 101 nearby though is Sunnyvale:
http://www.yelp.com/biz/sunnyvale-skate-park-sunnyvaleThere is a montage of this park in Bag of Suck. I've heard some people complain about this park, but its never been a good complaint. Sunnyvale is the best park in California. Its fun for days. Sometimes it gets crowded, but whatever, that place is amazing.
Santa Cruz park is dope if you are going through there:
http://santacruzskatepark.blogspot.com/Its got a full pipe, but the locals in Santa Cruz are kind of... unfriendly to tourists, to put it politely.