I pretty much have those same memories – in the same place, and around the same time, too (to IL from WI in the 70’s). That particular oasis is still kinda neat to sit at and look down on traffic – kids like it!
I’ve stopped at many, and yes, they are not as fun as they were when I was a kid. Food Court with Gas Station pretty much sums it up.
The better ones are off the toll roads, and in the middle of nowhere (I"m thinking my NOLA to MEMPHIS drives), where they have a rest room, and maps and tour brochures, and usually a play area for the kids, and some shade trees. And vending machines. Usually no restaurants, though.