If you will be in the Caribbean, Mexico, or some place like that in the near future, I'd probably skip Discovery Cove and just focus more on theme parks in Orlando (You'll have great snorkeling, dolphin swim opportunities, things like that on your other vacation.) What Discovery Cove offers is your Caribbean beach day experience and dolphin swim experience right in the middle of central Florida. And it's pricey as they had to build everything from scratch and aren't located on the ocean.
Most people who go to Discovery Cove really enjoy it and think it's worth it. It's a lovely setting, and they do a good job caring for the animals.
What really cuts the price down for some are the package deals that include Discovery Cove, SeaWorld, Aquatica, and Busch Gardens. But that's only a good option if you want to do all four of those.
When we have done Discovery Cove we have just gone there and to SeaWorld (love that park). Note though we usually skip Discovery Cove, as we get to the Caribbean/Mexico pretty regularly.