It is probably the best, but if you are looking for a bargain hang around the OXXO in PM. There's an expat guy who has a funky looking shop right across the street who is cheap, flexible, and more than willing to negotiate. Sure, he drinks a bit, but he'll take you wherever you want to go cheerfully.

btw, don't be shy about asking for PLAT upgrades at the St. Regis. We were there in Nov 2011 using Free Resort Nights for Garden View room. The paid rate would have been $470/night. Thanks to the persistence (!) of my wife, we were upgraded to a Deluxe Ocean Front Suite, which a time of check in was going for $2000/night.