Hi!!!
We really enjoyed our day at Aquatica and it was mainly down to having the cabana and our own private space!!
HOWEVER - A few things to consider - we were really lucky with the one we had - it was very private and because of what I had I read on the Seaworld board, I knew that some of the cabanas were located next to a smoking area - so I asked to be away from that. We were just lucky and got the last cabana near the kids area which was perfect for our boys.
But if we had been given the cabana just next door to us, DH said he wouldn't have been happy as there was a big umbrella right outside it and it seemed ANYONE could just use it - so not so secluded and private as ours.
The main reason we benefitted from the cabana was because Lucas (DS who was then 9mths) was able to take a long nap (over 2 hours!!!

) in the cool airconditioned tent, which meant we could take in turns playing with Kai (DS4) in the water - But I guess if we didn't have Lucas then we wouldn't have got much out of the cabana - but for little ones who need shade it was perfect!!
With regards to cost - we felt it was worthwhile but only because it included all of our drinks (we were able to swap what we were given for drinks that we preferred - and even had a couple left to take home

) but also because you get a discount (I think it was 25% off) voucher to use in the merchandise shop and DH bought a pair of Oakley sunglasses which he had planned on buying later at the outlet and we made big savings there - so it offset the cost a bit for us - but again it was great for us but I can see how others would find it very expensive!!
All in all - we had a great day - but it was a one off and we wouldn't hurry back to Aquatica (we much prefer BB - and please don't go just for the dolphin plunge slide as I didn't meet one person all day who actually saw the dolphins as they flew through!!

) - and I would really only consider the cabana if you have a baby who needs some shade for naps etc!!
hope that helps a little - any questions let me know!!!