Worst Hilton I have ever stay in!!! DO NOT STAY HERE
I'm a frequent Chicago traveler and this Hilton is by far the worst I have ever stayed in.
Let me star by saying we did not intend to stay inside the airport this hotel was booked last minute and the location was disclosed after we payed for the hotel.
It was my husband and our two kids traveling to a concert at the Allstate arena. We arrived to terminal 2 inside the airport and pulled in to the hotel and waited for the valet parking staff to guide us on how parking works here.
After a few minutes a guy peaked out the door did not great us or walked to the van we where driving he just pointed and said "self park its that building and its $33 per night then he turned around and walked back inside. First rude person here.
After we found our way to the self park ( very confusing if you are not familiar with O' Hare airport) we walked to the front desk with 2 people attending guest one its in the Hilton honors and the other one its the regular guests. We waited and waited the finally we got someone again very rude just said "next in line" again no greeting and no smile got check in and got our room. 
First thing we noticed its two tiny double beds and a very tiny room. I called and asked if there was a bigger room available we have two kids a boy and a girl 13 and 10. beds are very small and we can hardly walk in the room since its so small.
They said all they had its a suite with a king bed and no pull out sofa and they made sure to tell us since we booked using Hotwire they are not going to do much for us and to call Hotwire if we have any problems. So pretty much we just had to deal with it. 
Room was not clean very gross and unsanitary (see pics) but since we had not gotten anywhere with the hotel staff we just made the best of it.
We decided to take the kids to the pool we and found the first hotel staff that was nice to us a janitor pushing a cart with dirty linens.He smiled and help us find our way to the pool very friendly man. After the concert my husband order some food at the restaurant in the hotel and we got a $16 flavorless burger. 
Check out was the same way as the check in. no employees and no one to ask how was your stay no one smiling just busy travelers and unfriendly hotel staff after waiting for about 15 minutes to talk to someone. I just dropped my hotel door cards in a box and we left.
Bottom line stay here if you are stranded miles away from home. 
We will never be back here since I rather sleep in my van before coming back.