The Utah Education Association conference is that weekend. Apparently all the schools are closed so the educators can attend, and many families use the time to go to DLR! I think there are a couple of posts about it, but this year the dates are 10/16 and 10/17.
Just know that most of October isn't a slow time to go anymore, like it used to be!
There may be a day here or there, where one might be lucky enough to hit a less busy day, but overall, any time you choose in Oct. will be busy(at least busier than you would expect!)
We surely miss the "good old days" of "off season" October!