We just came back from WDW today (stayed at Pop Century Thursday, Friday, and Saturday nights) and we didn't think the crowds at Epcot were bad at all! Yes, the weekends are more crowded than weekdays, but the lines weren't bad and we were able to see, eat, and drink everything we were interested in.
The Magic Kingdom is always amazingly crowded on weekends, even during the slower seasons. The MK closed at 6 PM on Thurs and Friday for Mickey's Not So Scary Halloween Party, but closed at 10 PM on Saturday. We took the monorail over from Epcot Saturday night to see Wishes at 9 PM (left Epcot at 7:45 to give ourselves plenty of time).
The MK was quite crowded on Saturday night (we could not even guesstimate how many thousands of people were there to see Wishes), but you have to have a relaxed attitude if you are going to the MK on a weekend. You do not have to sit for an hour or two to reserve the "perfect" spot to wait for Wishes--any place on Main Street where the view is not blocked by trees will be just wonderful!
We stopped in a bakery on Main Street about 20 minutes prior to Wishes, and while the lines were a bit long, we were able to buy sandwiches and snacks in plenty of time to go out and watch Wishes. We found a fine spot 3 minutes before Wishes began.
We did not attempt to leave immediately after Wishes--instead, we walked on to a couple of rides while most of the crowd lined up for the 10 PM Spectromagic Parade.
We were lucky and only had to wait about 5 minutes for a bus back to Pop Century (mainly because we left during the parade instead of after). However, we have left the MK at closing time in the past and still have not had to wait all that long for transportation.
I know it's hard to have tired kids AND to be patient at the MK

--but if you are a party of adults, you shouldn't have any problem with the crowds during Regular and Value seasons from October through February (you couldn't make me go during the Thanksgiving or Christmas holidays though!).