I'm making my first foray to Cancun next month and was wondering if anyone could tell me about any must-sees down there. What shouldn't I miss (I'm going to be there seven nights)? What's the best way to get around? Should I worry about drinking water or should I buy bottled? Also of great importance, what's the best way to dial out to the States? I assume U.S. branded cellular phones won't function and the hotels usually charge a fortune. Am I better off buying a prepaid calling card or are the phone cards provided by the long distance service providers adequate?