"40 people is not a large group by Las Vegas standards, it's unlikely you're going to be offered any "freebies" for a group that size. Keep in mind these are hotels with 3,000 and 4,000 rooms, they deal with convention groups in the hundreds and thousands. It never hurts to ask, but if you've already booked your rooms there isn't much incentive to be gained by the hotel.

You don't mention the dates of your trip, keep in mind "March Madness" brings thousands of people to town to bet on the NCAA basketball tournaments. I think it's March 17-20 for the first round in 2011. "

And I have to ask about the " we have 4, 2 room suites..." part of your post. Is that a typo? Or are you going to have 10 women in each suite?? (Which probably won't be allowed by the hotel, much less the drama of 10 women sharing one bathroom!)