We stayed in Vegas for one night on our way home from
Disneyland last December. I was not impressed, and will not go back with kids.
We got a really great rate at Circus Circus, but the room felt old, run-down, and not all that safe, though we were fine. I just didn't like the feel. Included with our room, we got a coupon book that included 2 free arcade games. We also watched one of their free circus act shows, I believe they take place every 30 minutes. We saw a trapeze act, but the performers looked bored and like they were just going through the motions. I think the kids enjoyed it, though.
My overall impression of Vegas (it was my first time there) was not great. It just seemed dirty, and smelled like stale cigarette smoke on top of cheap perfume.
I am going back in March for a girl's trip, staying at Planet Hollywood this time, and hope to have a much better experience.
All in all, I'd say if we were going to attempt with kids again, we'd spend more money to be in a newer, more updated area.