航空公司.......

以下資料給你參考，全不包稅，其他附加費

(1) 達美航空 Delta Airlines (HKG--->ICN--->ORD)
出發日期 : 08/01/07 --- 28/02/07 (機票有效期:365天)
機票 : HKD$4980.00

(2) 大韓航空 Korean Airlines (HKG--->ICN--->ORD)
出發日期 : 01/01/07 --- 08/02/07
22/02/07 ----31/03/07 (機票有效期:365天)
機票 : HKD$5050.00

(3) 日本航空 Japan Airline (HKG-->NRT--->ORD)
出發日期 : 15/01/07 --- 09/02/07 (機票有效期:365天)
機票 : HKD$8450.00 (MON-THU)
HKD$8950.00 (FRI-SUN)

(4) 中華航空 China Airlines (HKG-->TPE-->ORD)
出發日期 : 15/01/07 --- 15/02/07
26/02/07 ----31/03/07 (機票有效期:365天)
機票 : HKD$9100.00

(5) 國泰 Cathay Pacific (HKG-->ORD)
出發日期 : 22Jan07 - 15Feb07
05Mar07 - 28Mar07
09Apr07 - 06Jul07
03Sep07 - 15Dec07 (機票有效期:365天)
機票 : HKD$13090.00

Currently, United Airlines is the only airlines to operate 10Weekly flight to Chicago from Hong Kong... However, as being the only carrier on the route, their fares are very expensive all year round of over HKD10000 include tax...
Alternatively, you can fly to Chicago via Tokyo (Narita) with ANA/JAL or via Seoul (Incheon) with Korean Airlines or Asiana Airlines... Flying those airlines provide a much cheaper tickets as competition on those routes are much higher and also with more flights operated...
If those are still a little too expensive, you can have a look at Philippine Airlines which should be even cheaper... But the services quality is much worse than any of those airlines listed above...
For fares, www.zuji.com do give you a pretty good idea of the fares... But sometimes you maybe able to get even cheaper tickets from travel agency...

www.zuji.com.hk
www.priceline.com.hk

you can search YOURSELF.