Gluttony refusing a free trip to Vegas (or anywhere) would have been like him refusing food. And Gluttony didn't turn anything down. He took whatever was handed to him, as long as it was fun and exciting and made him feel all warm and fuzzy inside. He had demanded food and drinks on the flight, an insatiable hunger and thirst that just couldn't be quenched. He needed more, wanted more. So he had as much as he wanted and then some.
During the flight he had kicked Greed roughly a few times and told him to calm down and stop being so fidgety. The best part of it was the Russian girl he had claimed for himself. Sneaking off to the bathroom at least twice had been the best part of the whole flight, considering how annoying Greed had been.
Once they landed he was ready to get off that plane and stretch his legs. He needed some good old fashioned sinful air. With his arm around his Russian (no, he would not be calling her by a name because that would imply he sees her as a living, breathing person with feelings and a family and he just didn't do that) he practically strutted down the terminal. "So, where to?" he asked the other three.