My wife and i always go in Sept. We usually leave the thursday after labor day and stay for 10 days. We've found that the week of labor day was a little less busy than the week after. We are actually planning on leaving the 4th this year because of the low crowds. However both of those weeks the longest wait time (other than Toy Story) was probably 20 mins. We actually had our own car for space mountain, and pirates that first week, and that was probably around mid morning.