[dukemagic]

i just put 4 people into a room for a trip last month. just put 2 on the reservation (since they do indeed charge you more for having more people in a room - at least, IP does) and when you go to check-in, make sure you only have 2 people at the desk. you can usually get an extra key or two by asking the front desk for one, saying "i tend to lose my keys - any chance i could get an extra one or two?"

just basically, don't be stupid and don't be really loud late at night, and you'll be fine.