I know this probably sounds silly but DH had the crab legs at Rainforest Cafe and LOVED them. We had to go back again before we left so he could have them again!!!
Gulliver's at the Swan. On certain nights,they have a seafood buffet with crab legs,shrimp and other items.Imho Excellent "in house" made desserts
Also you can try Fulton's for crab legs or Florida Stone Crab Claws if you are there early enogh in May. Stone Crab claw season ends May 14th.
Offsite the Orlando Ale House(off 535 near Crossroads area) at times has wonderful King Crab Legs and fresh fish. Good food Very reasonable Non resort pricing but gets noisy and very busy in the evenings.