We just returned Thursday evening from Cozumel. We've had friends, in differing groups visiting since May 30. The most recent couple visiting were going to be with us only 3 nights then head to Cozumel, we decided to head with them. It was a whirlwind trip, only 2 nights. We left Tuesday on the 9:40 bus, and got home Thursday evening about 8pm.
I had significant difficulty trying to get specific info on the buses, stations, locations, etc.
So here's what I learned.
I elected to travel via ADO. ADO GL offers a few additional extras that didn't seem to justify the extra expense to me for a short trip like this; Both ADO and ADO GL offer movies and or music, a/c (take a wrap because they keep it icy cold), restroom (take paper and sanitizing hand gel), reclining cushioned seats, window shades, ADO GL offers separate mens and womens bathrooms, baby changing area, a coffee/water/tea dispenser, and I think you get a soda when you board. Both buses list 5hrs 10min to 5hrs 35min as travel times
ADO was $286, ADO GL was $344, oh and they do give half price fares to those with the MX Govt INAPAM card.
Ticket Bus has good schedules; the site is a bit difficult to navigate, although they do show all levels of buses available within your search parameters. Be aware if you don't know which terminal you want in a location with more than one it can be frustrating.
Getting info from the attendants at CAME about which station we would arrive at in Playa del Carmen was frustrating. They really don't seem to know anything but what shows up on their computer terminal, and that didn't tell them much. And in typical Yucatecan fashion, they told me what they thought I wanted to hear, whether it was correct or not.
In Playa del Carmen there are two bus terminals. The older Terminal Turistica o Terminal Rustica, which is at 5th and Juarez is just 2 convenient blocks from the ferry. Unfortunately it only services 2nd class and local buses. The newer Terminal Alterna at 20th Avenue between Calle 12 and Calle 12Bis is where the 1st class buses arrive and depart; this is only about 8 blocks from the ferry, and if you've packed light can be a pleasant walk through the shopping area, taxis are available - we were charged $40 to be driven the distance from the Alterna Terminal to the Ferry.
Travel Yucatan has a pretty good PDC map, click here it shows the locations of the 2 bus terminals, and the ferry.
The Terminal codes for Merida Came are MEY, and for Playa del Carmen Alterna are PDC.
From Playa to Merida there is offered an Express Service, no stops, 4 hours and 15 minutes, these buses depart 0630, 1030, 1330, 1530, 1730, and 2359.
I'll have to go check on this Express Service availability at the CAME station and report back.