bear and summit are both empty during the week with like no lines at all.
weekends during the height of the season, with good conditions are fairly crowded but towards the end of the day it will die down, generally as soon as the sun goes down and it starts to get cold people run for the hills and the last hour, from 3-4 pm is generally the best, and you can get many many runs in.
it is definately bearable though, jsut go in the singles lines, even though it may be the longest, it is usually like 3-4x faster, and you don't have to worry as much about people dinging your nice board =). but if you can pick any times to go, the week is definately the best.
if you goto the snow summit website they have a live webcam that shows the beginner run and one of the express lifts and you can see how many people there are on the lift and run so it gives you and idea of how many people are there.
on weekdays the lift is pretty much empty, but take a look for yourself =)
Snow Summit: Live Web Cams
Click the streaming cam one