I would suggest Discovery Cove. For a birthday celebration, it's the best. I took my boyfriend for his birthday in March and suprised him with the 89 dollar birthday package, which consisted of a free picture, tshirt, bag, picture frame, and a buoy that said "happy birthday" that the dolphin carried in its mouth to him during out dolphin encounter. It's great with the aviary, stingray pool, and reef for snorkeling. The Atlantis is a gorgeous resort, but very expensive. Unless you're prepared to spend thousands of dollars to stay there, go to Discovery Cove. If you want a multiple day celebration, choose Atlantis, but do the dolphin swim or encounter or sea lion encounter at Blue Lagoon Island. There is a ferry across the street that takes you there and back. It's a beautiful lagoon and it's been there for a long time, so they're great at what they do. The Atlantis dolphin program is fairly new. dolphinencounters.com