I was there last year in Sept. (7th - 13th) and there were no, and I mean NO, lines for anything. We saw the Pocahontas show at the AK and we were the only people there, my DD7 got to go on stage with Pocahontas for photos. I think the longest we waited in line for any rides during the entire 7 days was about 20 minutes for Soarin, besides that the longest we waited was maybe 10 minutes, and that was for food! We had no touring plans and were in a group of 8 people for several days, including one toddler, and had no problems whatsoever. Right after Labor Day is the BEST time of year to go! The only thing I would suggest, based on our experience, is to make your ADRs in the parks you plan to visit each day, as we wasted a LOT of time traveling back & forth to different parks & resorts to meet our mealtimes. For example, if we had a 4:45 ADR at the Concourse Steakhouse and we were at Epcot, we had to stop what we were doing at around 3pm to make it to the monorail, head to the TTC, change monorails, head to the Contemporary, were done eating by around 7pm, then head back to Epcot for evening EMH, by that time Epcot had gotten much busier and we felt like we wasted 1/2 the day!
Ok, I got a little longwinded, but I hope I helped!