Agreed - hot stone therapy. My wife loved it.
Tulum beach - take a taxi from the ruins, or walk, to the El Paraiso cabanas. Along that stretch of beach, from the ruins to the rocks in front of Diamante K, both you and your wife can wear - or not wear :o - whatever you want. No problemo. A couple of bar/restaurant/cabana places (El Paraiso, La Vita e Bella) for food and drinks. Finish up the day with some drinks and guac at Gringo Daves. Be sure to post some pictures