Ken,
Wow. Impressive panorama. I do get to Chicago now and then so the view is familiar although it has never looked this good. Michigan Ave on the left edge, on Wacker looking north, I think. My favorite casual Chicago restaurant is only a few blocks away, Frontera Grill, at Clark and Illinois.
I have a Nikon D90 with the 18-200 VR Nikkor zoom but haven't had time for any pans since I got it. I do have an old Kaiden Kiwi panoramic head that I got for an earlier camera so the geometry doesn't quite match the zoom lens but for landscapes it will be fine. I had been using PanaVue ImageAssembler for quite a long time but recently moved up to a big dual-quad-core Mac desktop and PanaVue is Windows only. I have been playing around with using Lightroom/Photoshop but prefer an application devoted to stitching. I see that PTgui has a Mac OS X version so I'll have to take closer look at it.
A blank wall would look pretty good if you filled the top half with a four foot long version of your Chicago skyline above your Mississippi River Valley panorama.