We just stayed a week at the Carlton Inn, and it met our needs--and our budget--very well. We wanted an affordable hotel because of the length of our stay, and we needed a place to park that wouldn't bankrupt us. We also needed easy access to public transportation to get into the city each day (we had to drive TO Chicago, but prefer public transport, when we are there), and we wanted a hotel with free WiFi, breakfast, and microwave/refrigerator, if possible. The Carlton Inn came through on all accounts.
Others have already commented on the wonderful customer service here, and I agree. They gave us transit maps, dining recommendations, rides to and from the El stop when desired, and fulfilled every request (use of iron and ironing board, more tea bags at breakfast) immediately and pleasantly. They even bought my extra transit passes from me, when part of our party was not able to join us as planned, saving me a major hassle in trying to return them. (The Carlton Inn sells 1- and 3-day CTA passes as a service to their guests, but I had bought mine online before traveling to Chicago, and they had no obligation to help me out.)
Now, don't expect a newer, up-scale hotel that's just around the corner from Navy Pier. You'll pay a fortune for *that*. The Carlton Inn is older and about 20 minutes out from the Loop (plus a 5-10 minute walk to the station), but if you head into a stay with that knowledge, you will not be disappointed. The neighborhood is working-class, but doesn't feel dangerous, at least not as late as we were out. (We walked a lot and had two children with us, so I'm very safety-conscious.) There are many places to eat nearby, a mix of local restaurants--including a Giordano's (stuffed pizza)--and national chains. There's also a strip mall nearby, which came in handy.
Our room was a bit dark and the decor seemed a little worn, but it was very quiet, the AC worked beautifully, the TV was good, the WiFi was fast, the sheets and towels were fresh, clean and nice, the beds and pillows were great. Our bathroom was small and a bit dingy, but clean, and the shower was hot and strong. The breakfast isn't fantastic, but there's enough variety that everyone can find something they like: orange juice, apples, oranges, yogurt, donuts, bagels, and sausage/egg/cheese-on-bagel breakfast sandwiches.
Bottom line: This isn't the Ritz (or even the Hampton Inn), but it's as good a deal as you're likely to find in Chicago, and we wouldn't hesitate to stay here again.