The best place to find coupon inserts in the Chicago area is the Chicago Tribune. Other Sunday papers may have inserts, but I will guarantee you there will be fewer coupons, and even the same coupons may have LESS value. Did you know this? I learned it only recently. Here I thought coupons were coupons! When in doubt, buy the paper in your area with the largest circulation.
I have a Tribune delivered 7 days a week. I also buy additional Sunday papers on SATURDAY at the Dollar Store for only $1 a paper. Often I will buy the papers, remove the inserts, and leave the papers for the store staff to keep.
Recently I learned that the Tribune is currently offering a special Sunday paper promotions for 50 cents per paper:
Chicago Tribune Customer Service: 800-874-2863
Promotional Code: 09JE
Typically these promos have a short time frame (say 24 weeks) but you can very often renew them again at the same price. It's worth a call to them to check it out!