Add a significant addition along University Ave. and I see escalators and as many elevators as you would ever want connecting to the second deck. A nice concession area could be added as well as restrooms ALL UP ON THE SECOND LEVEL. I could also see the U going towards making a whole side of the 2nd deck a 'Club' with its own seating (similar to TCF Bank and Mariucci). I know they currently have a club, but lets be honest its a joke and needs to be totally rethought out.
GG2005 is on the right path with his ideas about the south/Univ. side of Williams Arena. A huge vertical struucture could be built between the sidewalk on Univ. Ave. all the way to the wall of the Historic(that awful 1959/60's era south lobby can be demolished) Williams Arena. A good outcome would be to alter the whole sideline on the bench sides going upward. There are extreme cost issues with this plan, but there is opportunity to remake the building.
I like the idea of creating a wall of suites and hospitality areas on the south sideline, like at Staples Center. This seating area would extend south above the current one story lobby all the way to University Avenue. The new exterior wall could be built with large, real windows to recreate what Williams Arena once looked like before they bricked up all the windows in a very cheap, ugly 1950's era remodel job.
A great deal could be done with the area behind the barnyard if the whole wall and deck areas towards the old hockey arena area were turned into something related to the BB side that extended further to the west into the pavilion area.
The problem with all of these plans is the quanset hut style design of the building and the shape of the roof. There is not a lot that can be done without spending a great deal of money. Sure you can add some lower level amenities and relief to those sitting on south sideline with a new structure next to Univ. Ave. You cannot do a whole lot about sightlines, elbow room, codes, or anything else.
Any sentimental attempt to do much is throwing good money at bad. The best option is to tear it down and build something with barn type features on the site. Basketball only, new facilities like Oregon and Missouri (Canseco Fieldhouse is another good example) are much better than hockey/basketball multipurpose mistakes like those that were built at UW, OSU and Penn State.
The Kohl Center is not all that great. Breslen Center, and even Hawk Carver (when full) mare better. The rest of the Big Ten Arenas have major issues.
Let them play at XCEL Energy Center for two years and start over.