I've haven't been yet, but am itching to go to Granite Peak at Rib Mountain in Wausau, WI. They seem to have expanded quite a bit in the last couple of years and have a 700' vertical, which is one of the highest in the Midwest. According to their website www.skigranitepeak.com
it's a 3.5-4 hour drive from Chicago. Maybe a bit far for up and back in 1 day but easily doable for an overnighter. And you get to ski 2 days.