We request the balcony because I like the view. And - the last time we sat on the floor my dad got picked to be in the show. I'm not saying it won't happen in the balcony, but he feels safer there. As for other participation, I think the balcony is a good spot. There aren't that many tables up there, and they send one of the cast upstairs during the welcome song.
We're huge HDD fans, and the last time we went (9:00 show) there were only two or three tables seated upstairs. Six-bits came up and we got to have a pretty long talk - if anyone heard us it was quite grizzly and unbearable.