San Cristóbal de Las Casas Warnings and Dangers

Ok, now I usually am not one to get car sick. I can travel on mountain roads in the US, no problem. But let me just tell you about the bus ride from HELL!
It started off by buying a ticket from San Cristobal to Oaxaca, a 13 hour overnight bus ride. I thought "overnight, this won't be bad" Well, we left at 10:30 at night. It started off with hard seats. I thought that I could handle that. About 2 hours into the ride, the air conditioning felt like it broke, so it started getting hot. Then we started on the two lane mountain roads: the bus was either going right or left, there was NO straight road. Topping it off by me not being able to see anything, I started getting sick to my stomach. We stopped somewhere in the middle of Mexico for about 45 minutes for a break. That helped a little to get off the bus, but then we had to get back on, and it started all over again. I finally told my friend to give me his bed roll and I said "I don't care who has walked in this aisle, I am laying down!" So I took the bedroll for my pillow, and laid down in the aisle. I was looking up at the ceiling while a little Mexican kid was looking down at me, very curious. I did that for the next 5 hours! I wasn't as sick, but it didn't make it go away. Needless to say, when we got to our destination, I was never so happy to be off a bus in my life.
So, my warning to you is, if you have to take the bus to or from San Cristobal, be prepared for a lot of curves, warm buses and hard seats! Take the plane in if you can!