In the interest of using fewer award miles, I booked a UA round trip BWI-LAX itinerary that includes a connection at ORD. A six-hour layover, from just before midnight to right around 6. Obviously, no matter what, I'm checking the bag I'd otherwise carry, but once I land, then what? Is there anything in ORD that is still open then or am I better off just napping by the gate for a few hours instead?