Hi,
I have been twice now to Orlando and I loved every minute - cant wait to go back again. As for Discovery Cove - I did that both times I went and would thoroughly recommend it.
You start your day in the reception where they take your photo and give you a pass - keep this after this day because it entitles you to entry to Sea World (and I think somewhere else too but that escapes my memory for a moment or five!) after your visit to DC! You are also told the time of your Dolphin Encounter and this is printed on your photo pass too along with the cove you need to go to. Then you move on to get your free morning drink before making your way into the 'resort'. On the way you have your complimentary family photo taken which you collect in the afternoon. You need to make your way down to the beach and changing rooms to change and get fitted for your life vest (which is compulsory when you are in the water). The just sit back and relax until your swim...
Being a bit of non swimmer (I can swim but not far and the water scares me, especially if I cant touch the floor!) it was a bit nervewracking getting in with the dolphins, however, the staff there are all very understanding and I didnt miss out on any of the encounter despite this, in fact, I got double the ride as I got a tow out and back in again, everyone else only had the ride back in!
The surroundings are wonderful too - a long lazy river which goes through a wildlife enclosure and takes about 40 mins to go round completely... a lovely beach, a cave which you can swim into, and a snorkel area. The food is all provided and is absolutely gorgeous... you will be stuffed after eating it (and I am a very fussy eater).
As for getting the tickets, I found it slightly cheaper booking online with them directly using a credit card. It was all very safe and a hassle free experience.
All in all, its expensive but very much worth it for the experience. You cant really do Florida without Discovery Cove!!
I hope this helps.