In one of the threads about this last year I talked about Hinkle Fieldhouse at Butler, which is probably the closest arena to the Barn. It was seriously renovated in 2014 and the U could take some pointers.
My thought would be that they should look at doing the following:
Building a large food court lounge area with modern amenities, food areas/bars and new restrooms on the south side of the building. Possible some kind of atrium entrance like Xcel has.
Eliminate all the bench seats except the student section. Put in modern seating - nobody wants to sit on a wooden bench.
Eliminate piss troughs in the old mens rooms.
Convert the upper deck on the ends to some kind of either suites or party decks.
See if there's a way to get some natural light in at the top of the building.
And finally, PUT BACK THE DAMN FINAL FOUR AND BIG TEN CHAMP BANNERS.
This is Hinkle today: