There are TONS of things to do in California besides theme parks. There's Hollywood, Beverly Hills, the Grove, the Queen Mary, San Diego, Santa Barbara, San Jose, San Francisco (one of my favorites), Sacramento... California is a huge state and it would take weeks for someone to experience the entire state, if they wanted to. California is one of the few places where you could go snowboarding/skiing, surfing, and hiking on the same day.
That sounds great!