The way that the press release is worded would indicate that rush is going to be available regularly:
"a limited number of Student Rush tickets will be sold on the day of the performance to students with a valid student ID for $35 (+ $2 fee). Two tickets per ID. Cash only. Rush tickets will be sold when the BO opens each day!"
The "based on availability" comment from their Facebook appears to refer to how many tickets they'll have for each performance. But it seems like they will have rush for most (if not all) performance.
The Marquis has really good sight lines all around (which, I guess, makes up for the lack of charm and Vegas feel you get from watching a show inside a hotel). I've sat all over the theatre and never found a bad seat. That said, I did treat myself to a Row D, dead center seat for my first performance on the 31st. Happy birthday to me.
"You travel alone because other people are only there to remind you how much that hook hurts that we all bit down on. Wait for that one day we can bite free and get back out there in space where we belong, sail back over water, over skies, into space, the hook finally out of our mouths and we wander back out there in space spawning to other planets never to return hurrah to earth and we'll look back and can't even see these lives here anymore. Only the taste of blood to remind us we ever existed. The earth is small. We're gone. We're dead. We're safe."
-John Guare, Landscape of the Body