dates, you can often find a room for up to 20% less than the advertised rack rates, particularly if you stay for more than a couple of days. Call several hotels and ask for the best possible rate. It's a good idea to reserve in advance during the peak seasons (January, February, July, and August).
Some hotels, particularly more expensive ones, quote prices in U.S. dollars rather than pesos. Visitors from abroad are exempt from the 19% sales tax, provided they pay in foreign currency or with an overseas credit card.