Depends on what you want to do at the beach. My sister used to live in Satellite Beach, FL, so we are used to going to the "non-touristy" beaches. Personally the prices are better and during spring break the crowds can be almost non-existent. If you want to be in the crowds, then go to Daytona or Cocoa Beach.
Last year we headed south and found a wonderful beach. It was near Jupiter, FL and was called Juno Beach. They had a wonderful turtle rescue center that we visited and it was a nice clean beach and nice town. I will definitely be going back there. We went county by county clear down to Miami. My favorite area was between Vero Beach down to Boca Raton. Beyond that Ft. Lauderdale, etc. I thought was very crowded and not real pleasant.
Remember, this is just my opinion. But I'm not overly impressed with Cocoa Beach or Daytona nor am I impressed with Ft. Lauderdale down to Miami .
We've been going to FL for spring break for several years. My sister says that St. Augustine is awesome, very nice and lots of fun. Haunted tours, a tourist bus that runs around town so you can get off at any stop, spend time and get back on. She HIGHLY recommends it. I have not been yet, but last year we were sitting in the hot tub at the hotel and another couple said St. Augustine was their favorite Florida coastal town to visit. It's further north.
Check out each county's parks & recreation websites. They offer lots of neat community swimming pools, fun things to do and offer suggestions that are reasonably priced.

We found an awesome small water park in Boca Raton that was about $8 admission. Think like a local and go the opposite way of all the crowds. There are tons of public access beach areas all up and down A1A (the coast highway). So drive down the highway and stop when you feel like it. I feel that you get to see what Florida really looks like, not just the tourist trap version, if you act like a local.
The further south you head the more beautiful the water gets. Around Cocoa Beach it's not usually the beautiful blue green postcard water. When you get around Juno Beach, Boca...that's when it starts getting the beautiful color to it.
BTW, Brevard County (near Cocoa Beach) also has an awesome zoo. You can actually take a kayak ride thru the zoo. My kids loved it, even my teenage daughter and her friend.