Any chain restaurant is fine. They're all the same; that's how they've gotten big. People like them.

Arby's is good (menu based around roast beef sandwiches). But my favorite nationwide fast food for road trips is probably Wendy's. It seems to be the highest quality of the big chains. Get a Frostee for dessert. Hardee's/Jack in the Box are fine too.

Bennigans and Applebees are like a TGI Fridays. In that vein, I tend to like Chili's the best. For the novelty, you might also check out Cracker Barrel, a chain of old-timey "country kitchens" and a country general store. Everything is tasty fried goodness. Their pancakes are great.

Depending how far south you get in small-town Illinois, you could potentially jump over the river to Missouri or Kentucky and go to Waffle House. It's a Southern chain of all-breakfast, open-24-hours restaurants. Think grits, eggs, bacon, biscuits and gravy. You know, health food.

I would also suggest Panera, which you will likely find in some of the bigger small towns. They've got good sandwiches, salads, and pastries. Panera is by far the healthiest of the options - everything's made fresh when ordered. Their breads are great - it was originally called the St Louis Bread Company - and baked fresh in the store every day.

That all said, when I go on road trips I make it a point to eat at small locally owned places as much as possible. Support the local economy and usually discover some great local color - a true slice of Americana. At worst, you'll have a mediocre meal. Quite often it's great home cooking, however.

In Arizona, you should probably check out the Grand Canyon.