As someone who attends VT games regularly in Cassell, I can report:
1.) Bathrooms are big enough, have enough stalls/urinals, etc. -- no standing in line.
2.) Concession stands are numerous, easy to get to, typically don't have long lines.
3.) Coliseum generally clears out quickly, so getting out isn't a big issue.
4.) Many, many seats are very close to the floor for great viewing.
5.) I love how densely packed the seats are, and how steeply banked they are. You can't do that in new construction, due to code.
I only have two complaints that a brand new arena would solve:
1.) Thanks to the fattening up of America over the last 50 years, the seats are too small. I fit in them just fine (I'm placekicker-sized), but several times this year, I've had people next to me who were just too damn fat to fit in their seats, and their fat arms and fat thighs spilled out over into my personal space. In one recent game, the girl next to me wasn't hugely fat, but her thighs were big enough that they were pressed up against mine the whole game. Blech. In a game back in January, the fat guy next to me had fat arms and shoulders that spilled out of his seating space and into mine. I leaned forward the whole game to avoid having this guy pressing up against me. Gross. Lose some weight. A new arena would, I hope, have larger seats and more room.
2.) Because of the nature of Cassell's construction, you can't "ring" the floor with students, because their standing all game would block the view of the money donors behind them. Contrast that with, say, NC State's arena, where students ring the floor and stand, but they don't block the view of the people behind them. (Click here to see how it's done.)
So ... why does Cassell "need" to be upgraded? So it will be ... prettier? So we can have big concourses to walk around in? So we can have concerts there? Pffffftttt. Cassell's a pit, when fully loaded with motivated fans. I like it that way.