I've been to Mexico five times for vacations over the past ten years. Taxis are inexpensive and the service is very good so I would opt for a taxi unless you really feel a need to have a car for other reasons. Blast's points are spot on. I've always been in tourist areas and have never had problems with any of the people or the language barrier; I don't speak Spanish. Mexican's can park cars in the smallest of spaces, another reason to take a taxi unless you are good at that sort of thing -not one of my strong points.

Cash - carry small bills, they always seem to have problems changing larger bills. I usually start with a couple hundred US dollars, nothing larger than a $10, lots of $1's, and then hit a cash machine as soon as I can. You'll get a great exchange rate via a cash machine - better than a bank or on a street. Also take out larger quantities of cash to avoid too many atm fees.

Stomach -I generally get a touch of problems each trip. This past year I finally got smart. I started taking Pepto Bismol morning and night every day as a precaution. That seemed to work well. Rather than waiting for symptoms to appear, get ahead of the game. If symptoms start to appear, then add imodium. I had no problems this year for the first time.

Puerto Vallarta was my first trip to Mexico, I wish I were there now.