On my first date with my current girl friend, we were originally suposed to go to an event in SF, luckily I realized that if I wasn't on a date I would never even consider doing anything like that and instead I just took her on a hike on the coast something that I would enjoy with or without her...
In general take her to do something that you really enjoy doing. She is there to get a feel for you and have a glimpse at what type of person you are. So be yourself and as long as you are doing something you enjoy it cant go wrong.
I dont know what part of NorCal your in but Point Reyes is a an awesome place.
PS: Keeping a blanket in the back of the 4runner is never a bad idea! And having a way to make tea is also clutch
