Well, if I were you, I'd take I-80 all the way from North Platte to Lincoln then take 77 down to Manhatten, as both Manhattan and Lincoln are college towns and have more to do.

But if your intention is just the scenary en route and not the stops, I couldn't tell you which is better, having never been on 24. But I-80 in Nebraska is generally considered a boring drive, scenery-wise. But fast, and maybe not so boring to people not used to the Midwest.