I'll second Courthouse and Rockridge, especially Rockridge. I love that spot and the vibes there are always great.
Another good one is Bella Vista park in Oakland. It's a little city approved DIY attached to an elementary school. Lots of mellow ledges, manny pads, and few ramps, and a halfpipe. It doesn't seem like it gets too busy and the people there are usually really friendly. It's pretty much the only spot that my friend who lives in Oakland skates.