I've been mid May and late May. Mid May was great. Lower crowds, nice weather. Late May we had some days at the end (really June 1 and 2) where it got really hot, and it did get more crowded.
October - I've been a couple times in Oct (normally mid-month). One year, it was actually chilly. It was warmer that Dec. We could not swim, but when I was back 2 months later, we were in the water. Maybe a fluke? The second time I was there in late October and it was great. We could be in the water, crowds were light. Overall, we had a great time.
Nov. - only been once this month, mid-month. It was very nice weather wise, and we had a great time. I just would prefer to wait a bit longer and get the Christmas decorations.
My favorite time to go is early December. Weather is hit-or-miss. Most years, we get at least a couple swimming days in and I love the Christmas decorations.
I've been once in Sept. and hated it weather-wise. Just way too hot. But then again, I prefer the cooler months.