bullin...,I go to AC twice a year and always take cash (lots of small to large). You can use the ATM but it will cost you. Check with you bank and see what out of country processing fee they will hit you with (3-5%). The local ATM's will also charge a fee on the spot. Visa and MC are accepted most everywhere, but not Am. Ex. in many places. One of the most popular restaurants is Estel's and they are cash only. Yes most street vendors are cash and small restaurants. Traveler's check are OK, but if the home you are staying has a safe you can use, bring cash and only carry what you need for the day.
Have fun!!!

"Hold on Tight To Your Dreams" ELO