Just wanted to add my experience...
We attended
HHN last year on the Thursday (10/30) before Halloween. We did S&S and had Express. We toured 3 houses without Express (not much of a wait) when we were first let out of the holding area, then ALL houses with Express, Bill & Ted's and Brian Bushwood (not in that order). The only thing we didn't do was Rocky Horror as we weren't interested in seeing it. We had time to tour each of the scare zones numerous times and we even managed to have time to eat pizza, have a couple blood bags and do a bit of shopping. We only do food, drinks & shopping after we've finished seeing everything we want to see. Yes, it was crowded but not uncomfortably so. As 2 of the experts (that would be Metro & Macraven, of course) already said...get Express (and do S&S) and everything will be fine.