Hi, I posted over there about immunizations. Here's my humble opinion, I like to be prepared.
I am a nurse and a Girl Scout.
I would definately update your tetanus if needed. It's something you should do anyway. Tetanus boosters can give you a sore arm for a few days, so why suffer on your vacation, if the need arose.
Hep A shots. Like I said in the other post, you can get it anywhere, from eating contaminated foods. Mexico has a high risk for Hep A. Click on the countries where hepatitis A is common
http://www.cdc.gov/ncidod/diseases/hepatitis/a/fact.htm
Hep B shots. You are less likely to have a problem here in the states, with blood products as they are tested. However, in other countries are you willing to take that risk if the need should arise? I for one am not.
http://www.cdc.gov/ncidod/diseases/hepatitis/b/index.htm