Can you give us more info? What time of the year are you planning on coming? Are you going to have a rental car? Are you just planning on staying in Southern CA for those 2-3 weeks?
I'm just going to assume you're coming in summertime and based on that I'd say you will want 4-5 days in
Disneyland and California Adventures. In the off season you can usually get by with 3 days between the two, but with lines and crowds you'll want the extra day or two.
Seaworld is in San Diego. So if you have a car, I would recommend changing hotels and just staying down there for part of your trip. I would recommend doing San Diego Zoo, Seaworld Coronado Island for the beach and cutesy shops and Old Town for cute mexican inspired shopping and yummy mexican food. Seaworld can be done in a day, but the past couple of years they have run buy 1 day, get a 2nd day free promo so if you want, you can break it up into two days for the price of one. Also, the zoo can be done in one day, but it's a huge zoo and lots of walking so be sure to be there at opening and stay until closing and be prepared to walk all day! Also, in that vicinity you have
Legoland and The Wild Animal Park. I'm not a huge fan of either but just throwing a few things out there to look into.
In the LA area you have universal studios, knotts berry farms (and a water park right next door but I can't remember the name now) and magic mountain. Depending on how big of a thrill seeker your daughter is would determine the best theme park. But it's something else you can look at their websites for.
And also (again assuming it's spring/summertime) if you're a baseball fan, you have LA Dodgers, Anaheim Angels and San Diego Padres games you can check out while you're in town.