I was looking at Room 1520 (19 E. 21 Street) for my wedding. I so wish I could have afforded it. The high cost mostly comes from catering - in which you must use caterers on their list. It may be in your budget though! It's a beautiful space.
I am getting married at the Hyatt McCormick place grand ballroom this new years eve... it's a super convenient location and they give great discounted room / parking rates. The food there is top notch as well (we just had our tasting this past weekend) and were just blown away. We are having 150 guests but the ballroom can accommodate up to 400 I believe. You will pay a little more than what you may other places, but Stacy is the catering manager there and has made our lives so much easier. It
s like having a built in wedding planner. They take care of all the coordinating. I'm partial to Hyatts as I travel for work and stay there, but this is one of my favorites. Let me know if you have any other questions.
My cousin was married at the Bridgeport Arts Center this past August and it's such a cool venue, but you have to have a planner as it is basically a blank canvas and you have to bring in everything. Bar service was horrible through the company they contracted with. Just saying.
We used Art Revolution (600 W. Cermak) for our wedding 2 months ago and it was great. It's a big loft space so there's a lot you can do with it, and they were flexible about what vendors we used. It was also resonably priced compared to some of the other venues we considered.
Not sure with renovations on Northerly Island but the old control tower or tent are beautiful spaces. Promontory Point, while it is in Hyde Park, is another great venue. I recommend checking with Park District for spaces too - bathhouses, conservatories and all relatively inexpensive. Blackstone venue is very elegant and a favorite.