WorldCon is nowhere near as big as events such as DragonCon or GenCon. It also has a much older demographic. In fact, many of the younger people who attend are the kids/grandkids of those who attended 20 years ago when I first went. It's more of a professional sci-fi writers' convention (Hence the Hugo Awards) than a mass market one and it feels like the attendees are a VERY tight knit group and have been for decades. Many of the seminars are geared towards sci-fi/fantasy writers and the future of the different genre's. The vendor's, display, and art rooms were also very sparsely attended compared to what there was in '91.
The convention itself is not organized or run by professional conventioneers, but instead by amateur enthusiasts and volunteers. They busted their butts to do an often great job but the lack of experience comes through. Example was the Anime room. It was listed in the handbook (on the wrong page) and had a list of what they where showing but NOWHERE did it say WHERE the room was. There was also the situation of the head of logistics passing away just days before the convention started. Again though, they all did as best they could and many attendees where willing to lend a hand to help out when needed.
There are several other smaller sci-fi cons in Illinois, Capri-con, Windy-con, Chambanacon, etc that I hope I'll start being able to make.