We had our reception at B.B. Kings and I would highly recommend the place. We had a pretty large group in Vegas with us so it was hard to find something to accommodate a everyone the night before the wedding. We ended up having everyone meet at the piano bar at Harrahs. We were hoping everyone could enjoy the pianos but they ended up having karaoke that night. Either way it was still a good time and an easy place for everyone to meet. Other suggestions would be the chandelier bar at cosmopolitan or meeting up on freemont street in old town.
We wanted to but never did this -- we were planning on having our friends and family all go down to Fremont Street since everyone was interested in going. It ended up everyone wanted to go their separate ways, but it would be fun depending on how many people you have.
You could also all meet up for drinks in one of the hotel's bar first then go to dinner.