From now til Dec 24 is always the slowest couple of weeks in Vegas.
Yes, the National Rodeo is here, but that is nothing like a major convention, and it's too close to Xmas for major conventions.
Good rates should be available at hotels.com and similar sites for this time of year.
BTW, it is so slow that a lot of the shows take some time off from now until Dec 24.
Starting Dec 25, it gets very busy again.