The overnight bus ride to San Cristabol was exciting to say the least... I was never a big fan of roller coasters but beggers can't be choosers! Bring some vodka with you on the bus as they would provide the environment similar to that in a Russia resto!
Just a few miles from the city of San Cristóbal is a traditional Maya community called San Juan Chamula. There are organized tours you can take, but i highly recommend the one which gathers in front of the main church at 9:30am. There are two guides (or more depending on the number of people) who would take you there. One of them, Alex, is actually half Mayan and he speaks the lingo and is very fluent in English. It was very informative and educational. Definitely a must-to!
I stayed at the Backpackers' hostel and i have to say, it's one of the best ones i've ever stayed at.
I got a private room with own bath, shared with a fellow traveller i met and it was well worth it.
However, while i was there, some girls who stayed at the dorm rooms got their things stolen because the staff there broke their locks to clean out the lockers. The staff then just left their belongings in the laundry room where everyone had access.
Also, the 'tour' to Palenque is not actually a tour. It's part of the Bamba hop -on hop-off ride, and there is no tour guide. The driver we got was extremely rude and unpleasant. Just don't expect too much from it and you shoudl be fine.
Perhaps it is the political tension between the US and Mexico that had generated so much negative press about Mexico. All the while I was there, I did not feel especially unsafe than other places I have traveled alone to. I would absolutely jump on the plane to Mexico in a heartbeat when the next opportunity arises!