this is what I do for Vegas shows, it works most times because everyone there wants the bucks. I buy the cheapest seats for a show then arrive about 10 mins before show time then quite a lot of patrons are already seated, I discreetly wave a $20 dollar bill at the "greeter & seater" and ask politely can they upgrade me, they usually can, we got a banquette for Mama Mia and similar for Circque de Sol but don't let go of the money until you sit down. Good luck.