We loved our day there in 2012 and definitely want to go back.
If you have the money, on top of what you are already spending, the private cabanas are sooooooo relaxing and amazing. You have your own little private space, a hut with ceiling fan, your own fridge filled with drinks, your own locker in the hut, a basket filled with snacks all day long and a person that will run and get you anything you want so you don't have to. It has a table and 4 chairs under the ceiling fan then 2 loungers. We were over by the sting rays and the kids played in the sand at the foot of our deck, could go in the water and we could still see them.
In my opinion, the private space made the day even more special. It was the best 180.00 we spent all vacation.
And my kids loved Disney (it was their first trip) but they talk about Discovery Cove more!!!