I've been to Las Vegas just about every month of the year and Yes! there's never a bad time to be in Vegas. Although slow times are generally in the summer when its 100-110 degrees.
Las Vegas Weather
Spring is great for the
Spring Break Party Crowd if your in to that.
Fall is nice since the weather cools down a bit but overall if your outside in Vegas your probably around the pool or walking from AC enviroment to the next one.
Hotel prices vary quite a bit from the slow time of year to the highest season but the high season is typically large events, tradeshows, and weekends.
The great thing about Vegas is it works around your schedule whenever its go to go is when you should be there!!