Ritz Carlton Naples has traditionally been solid and has enough going on around the hotel to keep you occupied for a few days. Naples, Florida is absolutely beautiful and relaxing.
The Residence Inn Treasure Island is one of my favs. The 2 bedroom/2 bath suites are in the newer building and live like a condo. I've also stayed in their 1 bedroom & studio rooms which are decent. (tip: the elevator by the lobby is almost never used, rather than waiting for the one in the main building) Shops, restaurants all within walking distance, as are plenty of places to rent bikes/scooters/jet skis. John's Pass is a short distance north of there and has little shops and restaurants as well. The pool is alright, but the beach is fantastic. Busch Gardens / Legoland are both doable distances from there.
The Sheraton Sand Key is a very old property. They do their best with what they have to work with, but it really needs to be knocked down and rebuilt. They have large conference facilities, so the place is usually packed with conference-goers. Immediately north of the property is the Sand Key park, so the beach tends to be crowded there.
I'm not a fan of Clearwater Beach personally. WAY too crowded and sometimes the crowd isn't always desirable.
I'm in both areas regularly, so if you have any questions feel free to drop me a PM.