I just researched this as we had a late arrival and early departure from ORD. These were the main options I settled on (i.e.: that you might want to check out) in the Hilton and IHG programs:

Holiday Inn O'Hare Rosemont (where we stayed ^; shuttle runs every half hour on the half hour, 8-min ride; restaurant in hotel as mentioned above)

Intercontinental O'Hare (shuttle bus; reviews say this is a real treat and can be had for a good price; home to the Capitol Grille steakhouse)

Hilton O'Hare (right in the airport itself; reviews say the property is nothing special, but can't be beat for convenience)

Hilton Garden Inn O'Hare (shuttle bus; reviews are also very good)

Hope this helps!