I think Megadeth needs to take a couple years off. Sometimes you need to let the fans miss you for a bit before touring again. The way they keep touring almost nonstop for the last four years isn't doing them any favors when it comes to ticket sales.
I saw the first gigantour in 2005 and that tour was a big deal because Dave had put the band on hiatus for a few years while he recovered from some nerve damage he had in his hand. My show was at an amphitheater and it drew a pretty good sized crowd. I would say most of the reserved seats were filled. Having Dream Theater as the co-headliner helped a lot to but certainly Megadeth making their big comeback was the major draw for the tour. While I don't think they have to be like Metallica and take 5 or 6 years between albums, no one can deny that Megadeth really needs to take a vacation for a bit.