Dana, the loco gringo site Pat and Bob mentioned is a great site and mostly south of Isla (Originally Akumal and south but it has expanded area over the years) and they have a map where you can follow the whole coast all the way to Sian Kaan Biological http://www.cesiak.org/
This is where we stayed the last 3 years we visited Isla. It is about 4 blocks from the main beach of the island on the north end.
http://www.isla-mujeres.net/hotelxbuluha/
When you walk to Playa Norta there is a place called Tarzan's where you can get 2 chairs, small table, umbrella and wifi for about 7 bucks a day and you can either buy their beer or bring your own in a cooler. Nice chill spot and I have a really cool story about place but for another time.
We are booked again this year in Negril and are looking "so" forward to our trip there. We needed a change after 9 yearly trips to Isla and most definitely will go back again.
The earth is a big place and if I had big bucks there is a lot I would like to see.