I second yosemite. It was really cool when we went. Just bring lots and lots and lots of bug spray. and careful the cabins (at least back in 2002) were seriouslly bug infested. but outside of that it's really pretty. If you go up to northern Cali, there's a place called Crater Lake that is pretty cool. It used to be a volcano that exploded and became a crater with a lake in the middle of it. I've been there a few times and it's really cool as well.