Route 66 west from Chicago begins at a street sign, the Begin Route 66 marker near Adams Street and Michigan Avenue, and ends at Santa Monica. In between are two-lane roads and small-town main streets, the kind with vintage parking lots out front where a mid-size motorhome pulls in and the family climbs out to wander. The kitchen and the beds ride along the whole way, so the trip can run a week or longer without anyone hunting for a motel at dusk.
Summer heat is the other reason this is a motorhome trip. Travelers planning Route 66 out of Chicago ask for rigs with air conditioning, and a hookup at night keeps it running while everyone sleeps. A table that seats the whole group, lunch out of the fridge, and a bathroom between towns turn a long westbound day into an easy one.
Route 66 across Illinois, then on toward Santa Monica
The first days stay in Illinois, town to town on the old road, and there's no reason to hurry them. Springfield is the night to build the week around, because Springfield KOA Journey has pull-through sites with 50-amp service. That's enough to run the air through a hot evening and roll out in the morning without backing up.
Reserve that site before you book the rig. It's the anchor night of the Illinois leg, and the dates you hold there set the rest of the itinerary. Lincoln's New Salem and the rest of what Springfield offers a rig are on the Springfield RV page.
El Monte's Route 66 campground guide lists Litchfield Skyview, where you watch the drive-in screen from your site. Past that the nights are yours to piece together, and the road keeps going through a long run of states before it reaches the Pacific. Nobody has to drive it back, because El Monte RV runs one-way rentals between its US locations and suggests this route from Chicago to Los Angeles, so the motorhome is returned in Los Angeles.
Fish Lake Beach in Volo, the lake week in Lake County
Fish Lake Beach Camping Resort turns the rig into a lake house for a week. The site stays put while the days go to the sandy swim beach on Fish Lake, the heated pool, and pedal boats or kayaks out on the water, and evenings end at the pavilion with live music or karaoke. Guests write about staying a full summer week, and that's the right length for it.
The resort is about 45 minutes north of Chicago off US Route 12 and I-94, and its RV sites are full hookups with electric, water and sewer, so the tanks and the air conditioning are handled for the whole stay. The season runs early May through mid-October, which makes it a summer and early fall plan. El Monte RV names it as a campsite for its Chicago renters, along with Chicago Northwest KOA as a second option, so it also works as a first night out.
Lake County also holds Illinois Beach State Park in Zion and Chain O'Lakes State Park, and Indiana Dunes, with its dune climbs, sits just across the state line. If it's two of you chasing those shore weekends, a smaller rig suits them, and they're laid out on the Chicago campervan page. Starved Rock's canyons are covered on the Joliet and Naperville campervan pages.