I hope that this isn't considered advertising. I just believe that it a great tool if you want to do Cozumel on your own!
There is an awesome map that you purchase on the honor system (can you believe it!) at mapchick.com it includes a detailed map of Coz, great places to eat, drink, sights to see, etc.
I rented a Jeep and explored the Island. Had a wonderful time. The East side (or wild side) of Coz is absolutely beautiful! and not crowded. CAUTION! Be sure to swim only at the designated beaches as the currents on the East side are very dangerous.
Also, you have to go to Coconuts on the east side for at least a drink and to take in the view, it's awesome.
Mapchick.com also has maps of Riviera Maya, Cancun, Playa del Carmen, and Isla Mujeres