Cozumel has great diving but for avoiding the all inclusive thing...well it IS the highest volume cruise ship port in the Carribean...plus after the earthquake I hear its not all it was especially the diving. You can definately avoid the resorts in Costa, tons of great great hostels if you go you must MUST go to monteverde and at say at the
Pension Santa Elena. As a non-smoker you won't understand the majesty of spending a day smoking derby suave and drinking imperial on the patio. But you will atleast understand the beer part.
Random bike comment: We need a halloween alleycat that is all.