They accept both so it doesnt really matter. If i remember you might save a buck or 2 if you do pesos sometimes.
I just got back and wanted to say that you absolutely can talk down these prices because their are going to be people from every club outside competing with each other. I always look to shave off 20% or 25%, especially if you have a group.
Guys guys guys, only twice or thrice did we pay $40 but when we did, we got a table with that and one time bottle service...other times we got really cheap prices and then still got table service with tipping everytime we got served...majority of nights we ended up in Mandala as it seemed to have the best ratio (although that changed eventually) and we would pay like $30 and a couple of times we paid $25 to get into Mandala...you have to be able to haggle!