Call them!
No seriously... I just got back from Las Vegas on Saturday... We had a Piazza suite + adjoining luxury suite booked at the Venetian for a recent trade show... was about 2000 sq ft total, @ about $1000/ night. When we got there- they upgraded us to one of the high roller suites, (3000 sq ft, 2 huge bedrooms, 5 bathrooms, in suite gym, 2 "party showers" steam room, his and hers bathrooms for each bedroom, massive great room with 54" plasma and grand piano...) for the same price as the other 2.
Las Vegas is hurting right now due to economic situation, so deals abound for those that have the $$$.