Illinois just got its first LEED certified, 4-diamond hotel, Hotel Arista in Naperville, IL, which is about a 30 minute drive from downtown Chicago. They do a lot to conserve as much as possible, and this for a hotel that is a really nice and chic place to stay. The accommodations and service are great, I highly recommend staying there if you'll be visiting Chicago and don't mind a slight drive into the city!