Check out Coba, not that far from Tulum. Its a rare classic period Maya city
ruin in the lowlands. Incredible, and allot easier than the Guatemalan
highlands. Chitzen Itza is big but not really Maya. Tulum itself is a
beautiful late Mayan walled city ruin, and the beach there is said to be the
most beautiful beach in the world. Riding the buses away from the coast is a
great way to get around and to inoculate kids with a little third world
reality--relatively safely. my favorite home base in the area is Playa del
Carmen.

Dave