There are MANY east coast beaches that are highly recommended, but I am all in favor of the Gulf Coast beaches. The water is clearer, warmer and BLUE instead of GRAY! The water of the Atlantic beaches are just dirtier looking, but if that's where you want to go, here is my recommendations. We really like the Ocean City, MD/Rehobeth Beach, DE area; Assateague and Chincoteague Islands on the DELMARVA Peninsula are great with not as much traffic/touristy stuff; Sandbridge Beach, just south of Virginia Beach is marvelous; OBX in NC has some great beach towns and campgrounds. We are hitting Camp Hatteras this summer. On further south, Folly Beach in SC is really good; Edisto and Hunting Island are two of our favorites (see above comment about hurricane damage); Myrtle Beach is NOT even close to be a favorite. It is way too commercial; too many people and dirty looking water for me, but that's MY opinion. Jekyll Island, GA is quickly becoming one of our faves on the E coast and then on further down, there are many, many places in Florida.
We love the Gulf Shores, AL area and the water is a pretty turquoise and is clean. Destin is also another of our favorites, but it is beginning to get way too crowded for me now.
Opinions here, so not haters.