WN @ LAS has been a disaster lately, we were delayed last month for hours and then cancelled, luckily we were the first in line and grabbed the last 2 seats out of LAS to MSP the next day..........if not we would have been stranded\ed for days
If flying out of LAS I suggest an early flight as it gives you more options to actually get to you destination vs a flight like ours that was scheduled to depart around 4pm