Upon seeing those who opted for the dolphin experience at Xcaret in Mexico, I can tell you, it is NOT Sea World. The surroundings are very natural and the experience (although my husband and I couldn't afford it) looked AWESOME. It's definately one of those things that if your daughter is majorly "into" dolphins, she will LOVE. If you are talking about Xcaret for your dolphin experience, the park is HUGE. Way too much to see/do in a day (2 days even), so I can imagine that the dolphin experience will suck up much of your port time and you will miss out on many of the other exhibits the park has to offer.
If it were me, I know if I didn't book the dolphin thing, and my kids SAW that they could have had that experience...they might feel like they really missed out.
Hope this helps!