I just came back from Sarasota. I took a 500mm Sigma 4.5, which is way beyond your specs, but my wife got some excellent shots with a Panasonic Lumix FZ150K that I bought used for $180. I was jealous that she did well with 1lb worth of equipment whereas I was carrying 9lbs. Of course, i win on the detail, e.g.,
http://i1093.photobucket.com/albums/i436/oeriies/ducks%20and%20birds/greatbl...arasotafeb.jpg
I visited The Celery Fields, the creek directly next the the van Wezel arts center downtown, Centennial Park (also downtown), and the Oscar Scherer Park. I got good shots at the first 3, wheeas Oscar Scherer Park was by and large a denuded desert. Your mileage may vary in the summer.