The last week of October? Think somewhere between "can of sardines" and "overcrowded can of sardines". We went Oct 20 last year, and the lines for the houses were at an hour+ after about 8PM. I waited 40 min in the single rider line at RRR.
I highly suggest getting into USF before the park closes at 5PM. You'll get funneled into the street in front of the Blues Brothers show (over by Mummy), and once the park is cleared of day guests and the employees are ready, you'll get walked over to the soundstages to get into one of the houses early. You can either go through it a second time or go get in line for another house before the gates open and everyone else gets let in.