Fitting hiking shoes is never easy, although the lighter the shoe or boot, the easier the fit.
Here's the routine: The first step, so to speak, is to find an outdoor shoe supplier where there's a good boot fitter. Surely Chicago has that. Or, at the very least, go to a good shoe store under the guise of buying some new Jimmy Choo's, and have your feet carefully measured. Odds are they're different sizes, and may not even be the size you think (most people are about a half-size off).
Then, armed with your new, definitive knowledge, hit the hiking-shoe store. It's OK to have a list of name brands in hand, but do NOT buy on the basis of what boot someone recommends, even if it's someone of impeccable reputation like me. Every shoemaker uses a slightly different last (the mold on which the shoe is built) and every human foot is different. So matching the right shoe to the right foot is as much dumb luck as science.
Wear your own hiking socks, or have them along (don't pull some from the store's sock bin). Also, try the boots on late in the day when your feet will have swollen up a little. Try on three or four brands of shoes in the style you want a light hiker, for instance and try a couple sizes of each. Start with your known shoe size, and then try a half-size larger and smaller (each shoemaker's idea of what a size nine is, for instance, varies widely).
Now to the fit: You want a boot that feels comfortable, with no obvious pinch points. A heavier boot will require break in, so don't expect an all-leather boot to feel perfect right away. It should feel pretty good, though. You want the boot to feel snug but not tight in the heel, and with good wiggle room around the toes. It's also helpful to kick a hard object. If your toes hit the front of the boot, the boot is a little short. Walk around some, without distractions, and get a sense of how the foot is doing in the boot. If there's an incline around to walk up and down, do so.
Once you've made your decision, take the boots home and put them on. Spend an evening in them, watching TV or walking around the house. You want to get a longer-term feel for the boot, but you don't want to get them filthy in case you need to take them back. Then, start with short walks around the block, gradually increasing distance over three or four walks or hikes. You may find that it pays to swap out the insole the thing that slips inside the shoe that your feet rest upon for an after-market insole, such as one made by SuperFeet ($30; www.rei.com). That may result in a more comfortable, more supportive boot.
Otherwise, hike on! Shoes these days fit so well and are so comfortable, I'm sure you can find some that work well for you.