I'm back from a week in southern california. It was a good trip in that we had a great time but the boys didn't sleep very well and Milo was particularly testy. We went to 3 theme parks which I'll rate below...
1. Legoland - the best of them all, the best ease of use experience, very much designed with families in mind. I'd go here again and again.
2. San Diego Zoo - also very good, more low key, recommend going on the bus tour first.
3. Sea World - it was ok but also frustrating in that there was very little shade in the entire park. The shows were nice but not sure I'd come back here until Milo's a little older.
I recommend getting your tickets online so you can skip the ticket lines and getting there earlier the better. Again, Legoland was the bomb.