Nawlins is hands down the best site, in terms of Stadium, Food, Hotels, Bars..and easily the King when any combination of the 4 are mixed.
If the NFL didn't have to be impartial they would get a lion's share.
Miami, LA, and SF with a history of closer margins is the criteria that NO is behind on..and that is due to the potluck of elite NFC teams and/or weak AFC years that were blowouts.
P.S. With Saints' ownership, the league is always assured that NO will be a neutral site for ANY SuperBowl ever played.