Depends on the time of year for best shelling is what we've noticed. We have a condo in Sarasota and frequent Siesta Key Beach often. One January we collected over 100 sand dollars between two of us - we were giving away handfuls to people. Other times, we find olive shells, conch shells, and other types. Lately (these past couple of weeks) we haven't found any what we refer to as "decent, unbroken" shells when walking the beach.
There are a number of TS units in Sarasota as well as Longboat Key - you just need to put in an on-going search with RCI.