I've lived in south Florida for many years.....one place you should go is Flagler Beach, near St. Augustine. It's a funkly little town right on the beach, and it's about the only place left that looks like these beach towns did in the 50s. It is sooooo cool. You can "see" it in an afternoon. The ambiance is one that's virtually disappeared now.

May at night in north Florida can be chilly----and once you get south it will be VERY hot!

The beaches and national seashore around KSC are some of the best.   St. Augustine is also fun, but touisty.

At the very north east coast, around Jacksonville, is another historic community, Fernandina Beach, with the oldest operating bar in Florida! and lots of old gingerbread houses. Some of the beaches at Jax are nice, too, like Atlantic Beach and Jacksonville Beach. Once you get down around Pointe/Punte? Vedra, tho, it's all private and gated, new communities.

A bit before West Palm,  you'll get into all the high-rises and gated beach communities. Fort Lauderdale's downtown, tho, is really nice---quite different from the beach. The development does not stop, you won't be able to tell when you leave one town and enter another!

And of course there are whole books about MIami, which is like three or four "countries" in one place.

One big warning: in early or Mid-May, they have "Bike Week" in Daytona, and it is HUGE! If you like motorcycles, you'll love it. They come from all over the country. But it can get really rowdy, and you will not be able to find a place to stay within 20-30 miles. It lasts a week; you could google "Daytona BIke Week" to find the dates, and plan accordingly.

Also, at Cocoa Beach, you might take a look at RonJon's Surf Shop. I'm sure you'll see billboards, and it's definitely a tourist attraction, but trust nme, you will never see anything like it anywhere else! I hate shopping, but that place was fascinating. You don't even have to go in.