I cast my vote for the Atlantic coast, waves are bigger and great sunrises (for your morning walk on the beach). Our favorite is Daytona Beach (about 90 minute drive) a little more commercialized with a ton of stuff to see and do. Cocoa Beach is next on our list (just over an hour drive from WDW), quieter and more laid back and great for a leisurely beach day.
On the Gulf side there are several great Beaches in the Tampa/Sarasota area, awesome sunsets but little to no wave action. We like Clearwater beach, Treasure Island, Belleair Beach, Indian Rocks Beach these are all about a 2 hour drive from WDW. We like to stay in the area for a couple of days if we fly into Tampa.