I feel a little isolated with my opinion because so many people have found DC such an amazing experience, but I have to say that it is really not very good value for money.
Firstly, the Dolphin encounter is about as intimate and personal as the big pool in Seaworld, just with less people. It is not really a "swim" with dolphins, but more a 10 minute session of the dolphin eating fish, then dragging you 10 metres through the water.
The rest of the day is spent either in the reef pool or on the lazy river, which after a couple of hours can become quite dull.
I do not rate DC as an all-day activity, but if you cant book your dolphin encounter early, then you will be a bit trapped there for the day.
I think you will do as well to save the cash and spend it elsewhere. Go to Seaworld and stroke the dolphins there because DC is not really that once-in-a-lifetime experience that it is meant to be.
The lunch provided is excellent though, definitely no complaints about that.
Sorry to sound so negative, but I do think that DC is not the best way to spend so much money in Orlando.
Note - This is just my opinion of course.