My son goes to Sanibel Island every Feb. with his grandparents and comes back happy and well-rested... they relax on the beach, go out for casual dinners, it seems perfect for him...
I've heard others mention how nice the island is as well.

My 2 cents... Anna Maria Island or Holmes Beach. These are located south of Tampa. Rent a house (very reasonable) great beaches and a family atmosphere. There are many day trips within a short drive. Plus, this area is not too overdeveloped "Old Florida".

I have a time share in Long Boat Key and go for 2 weeks every summer. I love it. I actually live in Naples, Florida so Long Boat isn't far in distance but it is a very vacationing feeling place. I have never experienced more wonderful places to dine than on Long Boat Key. The beaches are great and there are a lot of kids staying at the many time shares. Maybe that would be an option for you, a time share for a week or two. Anyway, good luck.

SANIBEL !!!!!!!
It's a great place, low key, mile long beaches, good food....great vacation place ! Very good for children, too.
We've gone to Sanibel about 25 years.

There is a hotel on St. George or was about 5 years ago. i think it is the St. George Inn. There's a wonderful state park at the endof the island where you swim all day if you wish. The island wasn't very commercial when we were there.

Anna Maria Island!!! Beautiful (uncrowded) beaches, lots of lodging and dining choices and two good fishing piers. I agree that LBK is beautiful, but IMO, it would not be the place where you could relax with 5 kids. It is a very adult oriented resort community. AMI is very family friendly. From the island you can easily get to Mote Marine, which is a great research aquarium. If you're so inclined, they offer morning camps that vacationing kids can attend. South Florida Museum in Bradenton has a planetarium, Florida history Museum and and aquarium that houses two manatees. You can also catch a boat to Egmont Key where there's an old fort and lots of beach. There's plenty to do to keep you busy. For more information, check out the Manatee Chamber of commerce website.

Fort Myers is nice, great beach and just a little bit touristy.