I've been to the Zoo. It's absolutely fantastic. I spent the entire day there without a break basically (15 minutes for a sandwich and to go to the bathroom). I don't think I saw everything. Based on that I think it would indeed be logistically impossible to do that AND anything else on the same day, especially with a small child. It will be overkill for the child in both physical and mental ways and it most likely will be overkill for the parents, too.

I have not been to the park but would like to do that. But I have been to Seaworld. I was thoroughly shocked at how much money they were asking. I think the entry fee was $46 plus $8 for the car. Jesus Criminy, I thought. That better be worth it. Well, it was. I was quite positively surprised. I spent the whole day there, too. I saw the Shamu show during the day which has the advantage that you can take nice pictures. But I really like the idea of seeing that at night with the light effects. You could do that as the crowning achievement at the end of the day. Just time your visit so your son won't be completely exhausted by then.

Till