My 15 year old son had a delayed opening to his school this year (Sept 20), so we went to Disney, stayed for 5 nights/6days with the Magic your Way plan, we stayed at the All Star Movies, with 5 days hopper passes, free disney dining plan, all for $1,100 for 2 adults and a teen! Weather was great, NO LINES, just jumped right on to everything we wanted, no waiting for anything. We are totally wiped out, but had a great time, so go if ya can in September you won't be sorry!
P.S. we flew JetBlue for $89 each way
This is our second time in September. We had a great time the first time in 2004.