J.P.
Hi J.,
You should try the Comfort Inn at Richardson Road. I was told about this place when we were looking for a place for my baby shower a year and a half ago. I want to say it was like $100 to $150 to rent. The room we were in even had a little refrigerator, sink and coffee maker. If I'm not mistaking there were about 50 or so people at my shower and we were all pretty comfortable.
Here's the info:
Phone - ###-###-####
Address - 3610 West Outer Rd
Arnold, MO
Good luck with your search.