At the NY Hilton and Towers, you generally don't want an upgrade. The worst floors to be on are the executive ones, because there aren't nearly enough elevators to take you up there. At peak times, you can wait over 5 minutes to get an elevator either way.
I'm Diamond, and they usually upgrade me to one of the Exec floors, and I always ask them to move me down to teh 15th floor or lower.
I hate to say this, but this is one of the few Hiltons that I try and avoid...