We are going in October. The crowds will be thinner and the park is usually open from 9-8pm. That's 11 hours. I think Universal's side might close a bit early on the days that there is the Halloween Haunt, but if you have a one-day hopper pass you make sure the stuff on that side is done before hand. Anyway, I'll have my 6 year old son with me. He can go on most of the stuff, and he probably will. But I figure since we have the Disney pass for 4 days that one day at Universal might be enough. Last time I was there in 2009 we did the two day pass with my wife and it worked out well. If I remember correctly both days we were out of there by 5pm or so. It was at the same time of year........October. Anyway, just to save time and a bit of money I was figuring that it might make sense just for the one day pass. What do you think? Would the crowds be thin enough that we can peel through most of the stuff at both parks?