Cocoa Beach and New Smyrna Beach are the best beaches close to WDW, but I vote for Siesta Key. It is about an hour and forty-five minutes away, but it is one of the beat beaches in the country.
I second this.
The east coast does have better beaches than the west imo, but not that far north.
Siesta Key would definitely be my choice between any Atlantic or Gulf beach in that part of Florida.