In our 15 yrs of FTing, we would pass through Elkhart twice per year and most often stay for a night or two at Elkhart CG. FHU, reasonably priced with most discounts including the 15% SKPs. Extremely easy to get in and out. Sites plenty big to stay hooked up if you wish though not within, for me anyway, walking distance of groceries or a restaurant - guess about 1 mile + walk. Easy off either Elkhart exit of the IN turnpike depending on if you are heading East or West. Have never had to call for a reservation and never turned away. They do have a large overflow area (I've never needed it) so I would doubt they'd ever be in a position of turning someone away. In 15 yrs of staying in cgs 365 days per year, I don't remember any cg manager as friendly or professional as Gita, Owner/Mgr.
As to Chicago/ i80. I never found it too bad. Depends, as with most large cities, on what day and what time of day but even on the busiest of days its about an hour of hassle from where it gets busy to where it tapers back off. At the time we pulled a 40' fifth with a small semi tractor and I'd usually find a 18 wheeler going the speed I liked and ask on the CB if he minded if I tucked up behind him. Always said "yes" and I could pretty much relax and just watch his back side. He'd radio if something was up ahead that required slowing down or changing lanes. Nearly every time we'd end up with a semi riding on each side of us as well so it was like we were in a 'cradle'. JMO