Percentage wise, I haven't a clue. I do know that, for basic analogy, Gonzaga students have end zone to end zone seats. But Gonzaga students do not have each "end zone" per say. In the link below, Students have sections 103-107, lower.I don't disagree at all with your premise here. That said, I looked at Gonzaga's kennel seating. See article below, which is still accurate in terms of the 1,200 student seats (only 20% of capacity). Note in the article it says the student seating wraps around 3 sides of the kennel (including both end lines). In terms of quantity, it appears that students still have at least 1/3 of Martin Stadium. Of you were to take Section 27 away and replace it with the lower sideline and endzone seats, you would pretty much replicate the kennel example but with far more student seats, percentage wise.
https://www.gonzagabulletin.com/article_af361c1d-2975-549e-84ee-d13aa8d1ecdd.html
http://wsucougars.com/sports/2013/4/18/208262489.aspx (Martin Stadium)
At Beasley, the current seating charts don't even show the upper deck as available. But the students, who used to have about half of the seats, still must have at least a third of them, including the full baseline on their side. So Gonzaga has nothing on us, quality or quantity-wise.
An interesting aside on the Gonzaga article - they have a whopping 60 seat capacity in their kennel luxury boxes, but also have a club room with bar(s) for well-healed folk. This is something that could be done at Beasley pretty easily (well with the help of a couple of jackhammers). You could block off a couple-3 sections of the inside concourse, knock out the back wall and establish some box seats and a club room of sorts. MIght be worth the investment once we get a team that people actually want to come see.
http://www.spokesman.com/sports/team/gonzaga-basketball/seating-chart/
And by no means do I think they should have an entire lower level, "end zone to end zone" for WSU football. I was advocating for not moving them. Keep our students engaged, keep our students loud and a big part of the atmosphere. That is all.
Regarding small improvements, the whole luxury seats expansion has alcohol already. Because it's a closed area, they have control of alcohol coming and going... or actually the premise being not going. The beer garden premise is what they were attempting to start up, a couple years ago. It's just a non-starter. The WSLCB just isn't going to budge. Here is the link for licensing if you want to wade into it further. I've dabbled into this... it's a quagmire, to say the least.
https://lcb.wa.gov/licensing/apply-liquor-license
Doesn't include the TTB, but I don't think they give a rip, as long as they get their share.
Oregon State has "The Terrace" but not only is it a closed off area, but it's a "membership" only with a controlled people flow. Oregon has it's own liquor board, we have ours. Our's doesn't like the idea of breaking new ground, apparently. To be clear, it's odd to me the site still has drawings up, instead of real pictures... so I'm assuming this is up and running... ? Haven't been to Reser in decades.
THE TERRACE