Sorry to be a wet blanket on this, but you may want to check out some of the humane society-like sites on how these dolphins are treated and how shorten their life becomes in these environments. It's a real eye-opener.
FYI - there is a difference between a dolphin encounter and a dolphin swim. A dolphin encounter is you and a whole lot of other people standing in the water in a line to get a lecture about dolphins, the dolphins swim by you, do some tricks, any maybe you will get a chance to pet them. The dolphin swim on the other hand is what it is, a swim with the dolphins. If your daughter has her heart set on swimming with the dolphins then do not book the dolphin encounter. I haven't done this but have heard really good things from others who participated in the dolphin swim in Cozumel at Channunkaub National Park.
I am actually going on my own on this, found a new program at Chankanaab National Park. It is a Swim & Snorkle with Dolphins, and it cost just as much as the Cruise Line. If you want the website I visited, email me and I will send it to you privately. Just remember you will need to pay the $10 enterance fee and a taxi fee, but you will actually get to participate with the dolpin, and not just experiance it going by.