The airport is not that bad, and if you already have a seat assignment, they can't give it away until 10-15 minutes before the scheduled departure time.
Only if you are checking luggage will you likely need more time. I would avoid that if at all possible.
An hour or maybe a an hour and a half will be fine without checking luggage. Add another hour if you are.
LV airport yesterday was a breeze (5 minutes through security), and Reno B gates looked fine as I came through.
Since I was able to sneak onto an earleir flight standby, I was only in the airport for 40 minutes or so...
