This site is awesome, it lists how crowded Disney is going to be by date taking into account a ton of different factors, and makes suggestions on the best/worst parks to go to based on those factors as well.
http://www.touringplans.com/tp2/UG2_index.php?PageID=14
We have used this on our past few trips (just the calendar, not the whole plan thing...) and found it to be very accurate. This past month we were there in early Sept on a crowd 4-5 level and walked onto just about every single popular ride, no fastpasses needed even! (Although...early Sept is very hot, humid, and rainy still, so end of Sept/Oct would be much better weather wise I think!).
http://www.touringplans.com/tp2/UG2_index.php?PageID=14
We have used this on our past few trips (just the calendar, not the whole plan thing...) and found it to be very accurate. This past month we were there in early Sept on a crowd 4-5 level and walked onto just about every single popular ride, no fastpasses needed even! (Although...early Sept is very hot, humid, and rainy still, so end of Sept/Oct would be much better weather wise I think!).