Sorry, I haven't done that trip, but I have driven around in Mexico. I would suggest completely avoiding any toll roads; they are ripoffs that also keep you from seeing Mexico.

Be sure to stop for things as you go through. Don't miss Teotihuacan, El Tajin, Palenque or Chichen. Take time and stop if something looks interesting, even if it is not in your guide books.

Try to stay at hotels with off-street parking. These aren't necessarily more expensive than others.

One thing to look for; if you are driving along and the car ahead of you turns on the left turn signal, he or she is telling you it is safe for you to pass. He is not turning left. If you must turn left and a car is behind you, pull off, let him pass; then turn left.

If there is an accident, only wait for the police if absolutely necessarily. If you must wait, be sure to have proof of Mexican isurance on you or you may have to spend time in jail until you do have it.

Sounds like a great trip! Good luck!