We were there last year at that time, arriving the Saturday before Columbus Day and leaving on Fri.
On Sat., after checking in, we went to Blizzard Beach around 3pm. It was not very crowded but, obviously, it was getting close to closing time. We then went to MGM for supper and had a 75 min wait for Tower of Terror (fast passes were gone) but I think the reason for the long line (and the reason we were there) was because Tower was supposed to be closed for maintenance for the rest of the week (which actually didn't happen and so we waited that long for nothing -- later in the week we got a fast pass for it and so had no wait). I don't really know how the rest of the park was because that is all that we did.
On Sun. we went to MK and it was crowded, particularly in Fantasyland. We have been several times in the past during the same week and this was the most crowded I have ever seen the MK. However, it was still manageable, particularly with the fast pass. My guess, although I have never been in the summer, is that the crowd level would be light compared the summer crowds.
On Mon we went to AK -- I am pretty sure that it was early entry day there. We rode the Safari 1st, got a fast pass for later, rode the River Rapids with very little wait, got the the Lion King show about 30 minutes before showtime but did not get in (already full). Got a fast pass for Dinosaur and ate lunch while we waited for our time. Later we got into the bird show right at showtime. The walkways were extremely packed but with the fast pass we didn't really wait for much, except I think we had to wait at least 1/2 hour for the train to Conservation Station (there was no line for the return). We came back later in the week on a day when it did not open early and the crowd was light so I don't know if the reason it was so crowded was because of the early entry or because of the Monday holiday. MK remained crowded throughout the entire trip, but the other parks were not bad at all.
Also remember that there was a special deal last Oct. , where Disney hotel guests purchased 4 nights plus park passes and got 3 nights plus park passes free. That is why we decided to go in Oct, and probably a lot of other people did, too.
We still had a great time!