Is Disney EVER too crowded to have fun? In my opinion, Yes. The summertime is just the worst! Our first trip in 1992 was in August, and it was sticky, hot, crowded, and miserable. It isn't that we didn't have a good time; but the hot, humid weather and long lines (average 45 min to 1 hr per ride) made such an impression on us that we vowed never, ever to go again in the summertime!
Since then, we have been back in November (Thanksgiving), and it was an awesome time to go. Very uncrowded -- I know that the "official guides" say that Thanksgiving tends to be crowded, but we were there in 1997 and it was great.
'99 we went to
Disneyland, so that's a whole other experience.
2000, 2001, and 2002 we went during January each year. I was there at a conference, but my family did the Disney parks during the day when I was at the Swan and Dolphin - and they absolutely loved it. Total lack of crowds. Basically you just walk right up and get on any ride, with minimal wait time.
We bought our Disney Vacation club timeshare in 2002, so we're looking forward to going this year at Thanksgiving again. We're staying at the Beach Club villas for a week, and at the Grand Floridian for another few days.
I think you'll have a great time in October. The weather should be just perfect; not blazing hot or too cool. And the crowds should be very thin. Have fun!!
Brad