Last year my family was trying to decide where to go for our little side trip before going to WDW.

This was in Sept. I posted a thread last year asking for beach suggetions and got some great info

We didn't make any ressies. Which coast we picked would be based on any possible hurricanes. Luckily there weren't any so we went with our first choice, the gulf side. We visited Anna Marie island (the beach was lovely and very desserted) for a few hours. (no shells) My DD6 loved playing in the waves. It was later in the day so we didn't go swimming. We parked near some homes and walked out to the beach. In fact, it was so desserted that my DD took off her clothes and played in the water in her panties. We hadn't changed her into her suit as we didn't know what we would find at the beach. Since the sun was starting to set we didn't want to take time to go back to the car and get her suit-so panites only-she

it and hated to leave when it got dark. We tried to find a place to stay nearby, but all the beachy places were booked. And if I remember correctly from checking online before we left, they ran about $170/night and up.
We drove around for a awhile and since we were heading to Sanibel the next day, we decided to stay in Sarasota (Country Inns & Suites off the I-75). We stayed there for 2 nights. I think we paid about $48/night and the room was nice and included a free breakfast.
We drove to Sanibel the next day (Saturday) We stopped at a McD for lunch before we crossed the bridge(s). We were worried about parking, since it was a weekend, but it wasn't an issue. We went to the beach by the lighthouse. We loved that beach! Yes, the sand was made up of a lot of shells, but we enjoyed looking for whole ones. We brought home a ton of shells some of which my mom and DD surprised me with this Mother's Day and covered a keepsake box with some of the shells.

And the water was just great! Coming from So Cal where our ocean water is always chilly, the water at Sanibel was a welcome surprise.

It was really nice just to swim and float around in it. People with boats anchor off shore and it reminded me of when my family used to go to the Colorado River-very laidback and relaxed. We had a great time there.
The next day the woman at the front desk rec. we check out Siesta Key as it was very close by. We did. The sand there was very nice. The beach was very wide. Quite a walk to the water. And no shells. My DD again, enjoyed jumping the small waves.
We drove

from Sarasota towards WDW the last day looking for a Cracker Barrel restaurant the whole time. Why is it you can never find one when you want one?

My DD6 loves their chicken and dumplings-they're very similar to the ones we make at home.
Anyway, as far as what beach to pick would depend on how you want to spend your time. My family enjoys just relaxing, looking for shells, playing in the water, and making sandcastles. We don't like to lay out and get tan. And I think I would go crazy staying at the beach for more than a few days. I can only take so much relaxation

and sun

! We hope to go back to Sanibel this Sept. but the long drive might stop us. Maybe we'll check out St. Pete Beach this year.