Agree with the advice to see if the hotel will store your bags while you try to do something in the city or go to the mall/restaurant near the airport. As for Terminal 5 at ORD. Before security there is essentially nothing except for a McDonald's on the lower level. It is NOT a place you'd want to hang out in unless you had no choice. Post security, there are some new restaurants and of course the lounges (if you have access) but again its not really a destination you'd feel drawn to for extra time (in other words 4 hours before your flight is more than enough time in the terminal).

In summary try to get the hotel to store your bags (almost all will do it for free for a few hours0 and try do something outside/in the city (plenty of options on another part of FT).