If you are going to swim with the dolphins then I would suggest you travel further south (if you can) and try somewhere around Key Largo/ Islamoranda. There are a lot of different places that will take you out to swim with the dolphins down the keys and it will be more of an experience as in Discovery Cove it is all done in an enclosed pool and the dolphins pretty much stick to a routine (if you know what I mean?)
Either way if swimming with our marine buddies is the reason your going to Discovery cove then you'll have a good time anyways.. even though I think you'll probably find a bit scary before you actually get in..., once you are you'll love it!!! you'll want to do it again and again and again and again.. you can see where i'm going!