C.P.
My kids used to go to a Bright Horizons in Schaumburg, and I know that they allowed drop-ins. That center has sinced closed, but they have various other ones in the area, including one in Arl. Hts (near Dundee & Kennicott), one in Mt. Prospect (right off of Golf Road, just past Goebbert), two others in Schaumburg (one at Motorola and another at Roosevelt University by IKEA). I've got two friends who use Bright Horizons as a backup for emergency drop-ins, so I believe just about all of their centers accept drop-ins. Good luck!