My vote goes to Marco Island. But rent a house with its own pool and dock.

I would avoid Miami - went about 6 months ago, shocked at how disgusting the beaches were. I too recommend Sanibel/Captiva. It tends to be warmer, the gulf is calmer/better for younger kids, and, it is just more relaxed. If you can afford it: South Seas Resort has it all for families. Very clean, very safe.

I'm very partial to Sanibel. We use VRBO. Can't wait!

Marriott Marco Island has a terrific set of pools, the poolside
Naples Bay Resort and Marina, Bellasera (great location) or Naples Beach Hotel or the Waldorf i.e. Naples Grande (nice pool there too)
Edgewater was a little underwhelming but is right on beach and grants you access to the Naples Grande pool a short drive away.
This little place doesn't look like much but it has a pool on the water and gets surprisingly good reviews, good local restaurant nearby and easy acces to boat rentals for fishing & exploring www.theboathousemotel.com

What about the Tampa area? Lots of attractions, and plenty of beach towns as well.

Grand beach surfside- brand new hotel- right by bal Barbour

We are considering flying to FL for Spring break, and our ultimate plans will likely be dictated by flights. I'm hoping folks can suggest hotels/resorts that might appeal to kids age 3 through 12. Will rent a car and would probably prefer to stay a few days in two different areas.

We've been to Miami, Key West, Sanibel, Captiva, Estero, and Naples pre-kids.

We know the weather will be hit or miss...but at least it will be warmer there than in MD.

Also toying with the idea of a cruise or heading to the Caribbean...

Suggestions???

Fwiw, we don't need the ritz Carlton/high end (we just need clean), and we don't need kids clubs/childcare (but a pool with a slide and other kid activities would be a plus).

$6k is probably a realistic budget for air/hotel/car (we'll budget for food separately).