With Notre Dame already scheduled, they've pretty much played everyone that's a who's-who of college football other than perhaps Clemson and Oklahoma over the last decade or two. Well, OK, we've missed Texas too, so I guess that's another one that would be nice if it could be done.
I guess I'd love to have the tradition of one of the service academies coming to Camp Randall. Doesn't raise the football profile much, but that wouldn't matter to me.
Other than that, I don't have any major desire for them to play anybody. The Big-10 already offers a solid schedule so it's not like some schools who have to hunt quality opponents to up the quality of their schedule.
One issue is many SEC /ACC schools have non conference rivalries games that cross over. Clemson / South Carolina. FSU / Florida, Georgia/ Georgia Tech, Kentucky/ Louisville. Leaves limited window to schedule games. Then there are the “kickoff games” that in reality are network driven. Not many Universities want to give up a home game. While I would love to see more the challenge is scheduling is set years in advance.