Fifth time staying and happy every time
When we can't get a downtown Chicago hotel (using Priceline's 'Name Your Own Price' option) for under $110, we stay at the Renaissance O'Hare. It is a great facility but there is NOTHING to do within walking distance. If you don't have a car (and most of the time we don't) you are pretty much stuck in the middle of nowhere.
But, for a mere $2.50 you can ride downtown (or buy a three day pass) or get to O'Hare with no trouble at all. Staying right downtown is more fun, but paying $250 a night isn't.
This hotel is clean, the staff is friendly and there is WIFI in the lounge which works so-so. The rooms are large and bright. If you have kids with you, they will love watching the low flying planes coming and going to near-by O'Hare.