We honeymooned there two years ago and have been on both anniversaries!
We did WDW for five days/Universal for three on our honeymoon, and had plenty of time. Of course, we went in September, so no crowds.
We haven't done Discovery Cove, although I'm sure that's where you can get your dolphin fix.
I can give you some nightclub advice.
Make it to House of Blues on Sunday night, for S.I.N (service industry night). Hands down the best music in Orlando, only $6 to get in, and the place packs out! Dress up a little and you might get picked for VIP on the 2nd floor like we did last year.
Sky60 downtown is very cool. On a rooftop right before you get to Tabu on N. Orange Ave. It is outdoors and has cabanas.
We like Antigua on Church Street on Friday nights for hiphop night with DJ Magic Mike. Get there early, or you will wait in line for 2 hours.
Wall St. Plaza downtown off of N. Orange has two or three bars/clubs there, Slingapour's being the one I remember most.
It all depends on your mood and musical tastes. Unless you are into C&W and want to line-dance, downtown Orlando has ANYTHING you want. Just take a Downtown/Church St. exit on Friday or Saturday night, follow the traffic, park your car at one end of Orange Avenue and start walking.
