Aug 13-18. We checked in on the worst day ever to check in IMHO (first day of free dining). The crowds were manageable; at times it was very crowded- I think the heat had something to do with it.
We were not on free dining (DVC points-savings in itself

) and had a great time during lunch and dinner hours because that was when everyone was eating.

No joke... from 6-7pm, the lines weren't bad at all. However, when everyone started coming out of restaurants with full tummies, the lines got big again for attractions (around 8pm). Epcot was always packed in the evening because there are like 14 table service restaurants. We did join in the crowds on some nights by eating at table service restaurants, but we were staying concierge and were always quite full from the snacks.
If you utilize fast pass, it should be no problem. This is what we managed to do on the "dreaded" Mon, as everyone checked in on Sun and wanted to see MK. We had non-exp passes and on a whim decided to go:
1) Quick pace to POTC after rope drop (10 min wait)
2) Thunder Mt. TWO times (walk on)
3) Grabbed a fast pass for Splash Mt.
4) Small World- hey it was a walk on
5) Dumbo- hey it was 5 in, embrace the inner child.
6) Mickey's Philharmagic- 10min (we actually rode dumbo so we wouldn't have to wait 20 min)
7) Funnel cake in Sleepy Hollow
8) Splash Mt- fast pass, 5 min
I was with my parents the whole time and we are athletic and quite knowledgeable about Disney so we didn't really run into any long waits. We did Epcot on Wed, it wasn't so bad. DTD on Tues, not bad either. Got crowded at night though b/c of all the restaurants. Here was our Thurs at AK:
1) We did the Sunrise Safari for Concierge guests
2) Private breakfast at Tusker House
3) I grabbed EE fastpasses- Asia was awful. I wanted to see what they did since it was all new compared to our previous visit. It was literally bodies of people. Horrible. I wish they did something about this bottleneck. I waited 30 min in the FP line. Within 10 min of the park opening, EE aready formed a line 80 min long. The line wound around Anandapur FP were prob gone around 10 or 10:30 am.
4) Went back to eat the rest of breakfast with parents
5) We received Kilimanjaro Safari FP's from the Sunrise Safari so we rode it to compare it to our concierge tour. Standby 40 min
6) Rode EE on FP

standby around 2 hr, FP 10 min wait
7) Grabbed FPs for Kali River- standby was already over 60 min
8) Rode Primeval Whirl- 10 min
9) Rode Dinosaur- 20 min, but ride broke, took 10 min extra for them to fix it. No prob- it was a/c
10) Kali on FP- 90 min standby
11) Shopped and went back for a swim
Hope this gives you an idea of what to expect. I bet it will be less crowded in Sept as this was the first week and we haven't started school up north yet. As you can see, it's manageable. We went on the super headliners, which always seem to need FP when we're there.

We've only gone during Christmas times and we found that more manageable but that's b/c it's cooler weather and the decorations are beautiful. Aug isn't as much fun to go- it's really hot and people get cranky in the evenings (along with kids)

.