I looked at the seating chart yesterday and there are seats in the upper levels all around the arena, both North and South sides. About the same amount of available tix as there currently are for Wisconsin and Illinois. My guess is that NU has about 5,000 season ticket holders and sell another 1,000 to walk-up with the remainder going to visitors on a game by game basis. However, a good chunk (20%?) of the season ticket holders for any given game don't go and sell their tickets to visitors on the secondary market, for another 1,000 visiting fans. So for a decent Big 10 game you probably have 5,000 NU fans and 3,000 visitors, but the visitors are far more vocal and make more noise than their % of the attendance would suggest!