The Harold Washington Library, like any public library, is a glorified homeless shelter. Yeah, there are books, but there are also a lot of bums. They just find a nice table to sit at with their multi-purpose suitcase/trashcan/refrigerator and camp out until they get kicked out. Because it's such a big library, the bum to table ratio really isn't that bad, but don't worry, they're still everywhere.
If you can forget about the bums, it's actually a nice library. It's really big, so they do have a ton of books and other research materials. I actually used to study there in law school, so it's very possible to find a bum-free corner to do some reading.
The reason I'm counting this as someplace new is because I finally found their event room. Way up on the 9th floor, they have a room called the "Winter Garden" where they do corporate events and weddings. I thought it was going to suck, but it's actually awesome and probably a great place to have an event.