Ernie, we were there in September, and it was wonderful -- fall color and somewhat fewer folks. But don't make the mistake we almost made -- I decided not to go to the East side of the park because it was too crowded. Fortunately, DW decided I was wrong (nicely, of course).
She was right. Even if it is crowded, spend some time on the east side of the park, as well as the west side. There is a good reason that the whole park is crowded -- it is terrific.