Kuoni do a Treasures of the Yucatan tour with a possibility of beach or other extensions. They visit Tulum and Merida plus other places of interest.

Hayes and Jarvis do a Classic Yucatan tour, doesn't actually visit Tulum but does visit Merida and some other sites. Tulum is very easy to visit on your own from the beach resorts.

Judith

Personally I wouldn't let the whole trip hinge on Tulum, if it's a deal breaker on the tours. We did Coba and then Tulum and were very disappointed with Tulum. Coba was amazing, very raiders of the lost Ark, out in the jungle, climbing the pyramid with just the aid of a rope and really not too touristy. Tulum though, everything was roped off, with huge amounts of tours going around with their guides- we arrived early too, so I would hate to be there when it's really busy, the coach park was enormous!! It was very pretty, perched on the coast, and if you can stay nearby, worth a visit, but you don't need more than an hour or so there.

Enjoy your trip, Mexico was our best holiday ever- the children still talk about Coba and they were only 7 and 10. It's a wonderful country.

Pam

Personally i would do it yourself.

Base yourself in Playa del Carmen.

Tulum is a doddle to do by yourself as you can just catch a collectivo (cheap minibuses that run up and down the highway,that can be flagged down or picked up at stops on route) or you catch the ADO bus from the bus station in Playa itself.

Cozumel is a short ferry trip also from Playa

There are also a few trips that combine the ruins at Chichen itza with an overnight stay in Merida.
Or just catch the ADO straight to Merida

A really good trip that i personally would recommend is a day on Isla Mujeres. catch the ferry from Cancun,rent a golf cart and cruise round the whole island (its only around about 3 X 1 mile big and the only other real traffic is other golf carts)

We are going back to Playa in October and are also planning to go to Merida,we will also be doing the golf cart thing again On Isla as it was one of the best trips we did last time we went.