Thought I would add my 2 cents in! This is cut and paste from my review.
Costa Maya: This was our favorite port by far! I had read only a few reviews on this and had some input. Do not do the tours from the boat to the ruins! If you walk out and follow the signs to the taxis they have clearly marked signs for the rates, etc.
Majahual $ 5.00
Kohunlich $ 65.00
Chacchoben $ 45.00, the boat wanted $72
All prices are round trip and do not include guides.
The only bummer was that the prices were per person, but still cheaper than the boat. We went to Chacchoben and left around 9am and when we arrived, the tour buses were starting to leave so we had the place to ourselves. The Chacchoben Ruins are situated in a secluded jungle setting. We chose not to have a tour guide, but there were some available if you liked. Our driver were very polite and was learning English, this seemed to be the case for most people so don’t expect much conversation. At the site you could buy water, a few trinkets, etc. There were portapotties and that was about it. Use bug spray for the walk. There weren’t any signs marking for the important sites, but if you follow the paths you will see them. After we went on the trip we went back for lunch at the boat and then went snorkeling to the right of the pier. We saw the most amazing fish we’ve ever seen. You need aquashoes since it is rocky, Weird note: the water got warmer in pockets as you went in so the shallow part was actually the coldest, who knows why! Don’t miss this! Avoid going to the private beaches since there is so much right at the port. We didn’t really look at the shops, but there were a few, but definitely not a big shopping place. The pool with the bar looked nice, but we liked the snorkeling. It ended up raining in the afternoon, but we stayed in the water. Also, there was a free trolley to take you up and down the pier. There were also free shows with colorful costumes to enjoy. This is the first port where so many services have been free, free pools, shows, trolleys, etc.