If you do get stuck at ORD, and they won't put you up in a hotel, you can always try Priceline. You may be able to bid on PL and get a better price than the so-called "distressed passenger rate," which often is not that great of a discount.

If you check the web site
http://p070.ezboard.com/bpricelineandexpediabidding
you can get an idea of the bids people are making in the ORD area and what is working and what isn't. Another similar web site is
http://www.betterbidding.com

If UA/LH will not give you a hotel voucher, as a last effort, you could ask for a travel certificate. Once at an outstation on a UA Priceline ticket delayed by weather they would not give me a hotel voucher, but they ended up giving me 2 CR1 type domestic upgrades. Most people got zilch because they just didn't ask . I was then able to return to the hotel I was at, and get the same discounted rate I had extended for one night, and then got a double op up the next day, and again this was all on a Priceline ticket .