Bringing your kite gear might be best if you can. It's the windy season in the Bay Area, so you'd most likely be able to use it on any day you have time to. I think it might be possible to rent from Board Sports in Alameda (but not sure).
For info on locations and local knowledge, go to http://www.bayareakiteboarding.com
. Lots of good spots to ride, but make sure you read up on each one first. Some don't work all season long, so won't be worth trying. Others have hazards. Anyway, all that info is in the site guide on BAK. Hope you get some time in on the water!