Yeah the lines shouldn't be AS bad beings that school will have started, and hopefully there is a break in the weather. When we went in Aug. 2008, we actually did not have hot weather- only because we were stuck in Tropical Storm Fay the whole time we were there!!! However, I just returned from a "girls getaway" in June (dh and ds's mother's day present to me- I went with my good friend from work), and it was so hot that I was convinced that we were on the sun and not the earth those few days! I took a picture of a man's back, and he actually sweated out a Mickey Mouse head (it's too funny!) I actually think I preferred WDW during TS Fay rather than be in the heat- as we were able to walk right on most of the rides. We did get sick of changing clothes, and I had to blow dry our sneakers out every night with the hairdryer!!! But I do think that September will be a great time to go.
As far as the difference between the two
DDp's, they both have their advantages/disadvantages. I prefer the QSDP because of the mugs (great great great), the two snack credits, and I hated making ADR's and stopping what I was doing because I had to be somewhere for dinner on time. Also, on the regular DDP, you tend to order the most expensive thing on the menu to make up for what you paid for the DDP, but you have to remember to base your tip on that as well. With the QSDP, you are all set, and may only have to shell out a few bucks here and there for food. However, with the regular DDP, you do have better quality food, and can attend great functions such as character dinings. And beings that it may be free next year, even better!
And finally, I stayed at ASMo in 2008 when we took Austin and he loved it. If you are looking for great character themed rooms-as you may know from staying in the Toy Story building, this is the place to be. I think ASMo has the best hotel character setting in Disney and is great for the little ones (we stayed in the Dalmation Buildings). When I went in June, I wanted to test Pop Century before I came back with my DS and DH. The actual theming and setting is very cute. We stayed in the 50's section with the bowling pins and Lady and the Tramp. The rooms were ok, not as themed as ASMo with themed border/pictures or anything. Everything outside was so bright and colorful and the food court was HUGE compared to ASMo. We may stay at POP next time, I'm not sure yet, it depends on what characters Austin is into at the time.
We are probably going to go toward the middle/end of Sept. sometime- we definitely want to take full advantage of the free dining. And I might plan a surprise at DTD on the hot air balloon ride- not sure yet!!!!