We were just there with our GS troop. I'm not sure you'll need two days, unless one if for Aquatica?
We got to the park at 9am (Check the map and plan so you can see all the shows) and we were done, seen it all by park closing at 8pm!
The kids enjoyed it 'specially the dolphin touch tank. Me, I'm spoiled by the way Disney does things . . . so I was missing Disney ALL DAY!
Not sure about what they do at Xmas . . . I'm sure someone here will fill you in!
I did just find this listing with all the HOLIDAY SHOWS . . . looks great!
SeaWorld Christmas - Christmas in Orlando