Arrived Friday. Went to MK Friday afternoon and evening and the lines were great (7DMT was around 30 mins much of the evening, for example. Most things 10-15 mins or less across the board), though it was pretty rainy so that may have contributed.
Saturday went to water park. My brother and family went to MK and said it was busy, about like summer crowds from previous trips they've taken.
Sunday we went to Hollywood Studios--I thought it was pretty crowded (Touring Plans predicted 5/10 but ended up calling it 7/10) and awful--probably due to there only being 5 real rides, lines were long for everything unless you used FPs, and there were NO useful FP after using those three whatsoever. It was again very rainy, but that didn't seem to thin the crowds at all.
Went to Epcot this AM and Animal Kingdom 1-6 PM (Labor Day) and it wasn't too bad, definitely probably below average compared to most of the year, but not empty by any means.
Hoping for a much less busy Tues-Sat now that the weekend and holiday is over.