As someone already said...downtown Chicago is a long way. Expo is held in a very nice suburban region of Chicago. The immediate area plays host to several Corporate HQ's like Abbott Labs, Baxter Healthcare, Walgreens, Takeda, Kraft Foods. Allstate, ITW, CDW, Fortune Brands, etc. As you can imagine there are a bounty of higher quality hotels catering to this market.
If you head east from Expo, and not very far, you run into some of the wealthiest 'burbs in the country like Winnetka and Kenilworth.
Some ideas for nicer hotels from a local...Going south is a Hilton and a Crowne Plaza on Milwaukee Ave in Northbrook. There's Hyatt, Marriott Courtyard or Embassy Suites on Lake-Cook Road in Deerfield. Also in Deerfield near I-294 and Deerfield Road there's a nice Marriott Suites. Going north to Lincolnshire there a nice Hampton Inn on Milwaukee Ave, another Marriott Courtyard also on Milwaukee and of course the Lincolnshire Marriott Resort (old time place with a theater and spa). Going west to Buffalo Grove there's a Wyndham on Lake-Cook Rd. There are also many budget friendly places within 2 miles also...usual chains like BW and Motel 6.
If you're bringing the main squeeze you may like the Sybaris......