Drove I-80 from CA to Iowa last year. I made several stops to play courses in Nebraska.
Westbound, on the way home, I played Roper Park West...uhhh, just pulled it up and it is currently closed.... Well, if the replacement,
Roper Park East, is as good, and given that it looks easier to get to from the highway, you might check it out.
I also played
Lake Helen Rec Area in Gothenberg. I would only recommend this as
possibly the best place to play in between Big Springs and the Kearney area if you need a break.
If you don't take I-76 up to I-80, then you might consider
Deer Run Park in Sidney, NE. It is a bit better than its rating, as the trees have matured since the early reviews. Best access is from the same exit as Cabela's, so if you are thinking of stopping there....
For me time was a major consideration, as I had around 1800 miles to go in 3 days, and I had to balance quality with time and daylight.