I have this model of swim raft that I bought a few years ago at Production Dock and Trailer:
http://www.hewitt-roll-a-dock.com/ot..._platform.html
This model sits about 6 inches higher than others in the water. Although I didn't realize it when I bought it, this is an advantage as ducks and geese seem unwilling to jump the extra 6 inches out of the water. So they go and crap all over my neighbors' rafts instead.

There is a blue heron that likes to visit a few times during the summer, but so far he has been very polite.