We went to Majahual and to the ruins. We met Teresa from "El Tucan de Costa Maya S.A. de C.V." tours in Majahual. She spoke English very well and was very nice. The business card she gave me lists a number as
52+(983)83-459-11 or info@tucancostamaya.com.
I think you should contact her to arrange anything you want to do.
Cruisemamma, we went to the ruins with David from http://www.chacchobenruins.com/ I believe it was about 50 minutes to get there.
David and Ivan run a top-notch operation running tours of the recently excavated Chacchoben ruins. Ivan grew up right next to the site, and is intimately familiar with it. He was also raised in the Mayan religion, and spoke about the customs and rituals that shape the architecture of the ceremonial religious sites. It was THE best tour I've ever taken, bar none. I can't recommend them highly enough. Their tour company is called The Native One.
Good luck ... and enjoy Costa Maya in it's mostly pristine state while you can: There are FOR SALE signs everywhere, and a new casino and 3,500 room resort are supposed to start construction late in 2006. It'll be all over when that's done.
I have to agree with everyone who loves this port. Costa Maya is thumbs up for me too. I have been there twice in the last 6 months and love it. Tried Uvero Beach and Delphinus last time. Much rather go there than Cozumel.