For a great experience, indulge in the Mayan Bath at Maya Spa. You get a massage and soak in a wooden tub filled with flowers in a private, billowing, white-curtained tent on a rocky cliff overlooking the surf. Unbelievable.
But beware that the prices listed on their web site are out of date. They list the price for the Mayan Bath as $88, but they now charge $100. Also, I booked an appointment via their web site, but when I showed up, they had no record of it.
Luckily for me, a lovely young couple from Brooklyn gave me their appointment time and rescheduled themselves for the next day. (I couldn't reschedule because I was leaving the next day.)
Anyway... I don't know if the web booking doesn't work at all, or just malfunctions occasionally. But if you book that way, be sure to reconfirm before you show up.