I would recommend Sea World on your first day. There are fewer rides to queue up for and more shows to sit down and watch if you are feeling tired still from the trip. On all our previous visits there has always been some ticket offer on whereby you get an extra day free, so even if you feel you can't last all day Friday, you can always come back another day for free during your trip. I also notice that the park tickets link on this website currently have a special offer - Buy 1 day get 6 consecutive days free! Not sure if this will be valid for your date of travel but we'll certainly be taking advantage of it for our own forthcoming trip in August. Can't wait!

Animal Kingdom would also be a good bet especially if you are up very early that first morning. Head straight for the safari as you will see more animals earlier in the day. I believe that if you do the character breakfast there, you can get into the park earlier than it opens to the general public.

The swim on night of arrival sounds a great idea - we'll give that a try ourselves this trip.