I'll be the dissenting opinion. At 5 and 3, my kids much prefered Seaworld and could easily spend 2 days there. We spend lots of time feeding Sea Lions and Dolphins, touching sting rays and just looking around. Plus, to see every show in one day requires careful planning and too much sitting. Mine could never get enough of the Happy Harbor either. Unless you have other reasons to be in both Orlando and Tampa, I'd spend the two days at Seaworld (second day is often free if you pick up your pass before you leave.)