For $100 hamburgers out of Watertown...
Janesville has a new restaurant.
Sheboygan has yet another restaurant (check hours).
Pilot Pete's at Schaumburg, IL (06C) is one of the best airport restaurants around, IMO.
Oshkosh has a couple of places nearby if you park at the Hilton ramp.
A bit farther afield, I really like Three Lakes (40D, really nice lit grass field). Sunset Grill is across the street from the runway 21 threshold, or there's a tiki bar just down the way, I think you can rent boats right there, you can camp on the field (and there's a camp store in the same building as the Sunset Grill), etc... Really a great place to go.
If you want a great romantic night with the Mrs., fly down the Chicago lakeshore in that last hour before sunset. Land and eat at either KIGQ (Lynnie Que's BBQ) or 05C Griffith-Merrillville (Mi Tierra mexican). Make the return trip up the Chicago lakeshore at night. Or, fly up to Schoolcraft County (MI UP) and check out the stars - They're awesome up there. Or go stay overnight up by 6Y9 (cabins near the east end of the runway - And be sure to let
@Dizaster know you're coming!)
I'm looking forward to seeing the "Kids" ideas - Mine is still under 2 years old, but he LOVES airplanes. We've flown on some longer trips, but generally to get to functions with family and friends, and not day trips centered on him.