How can Miami host the most Super Bowl game?

1) Climate.
2) Logistics. Two major airports serving South Florida, and ample hotel supply (number of rooms).
3) Pro and college team nearby to provide practice facilities for teams.
4) Two cruise ports to provide additional lodging options if need be.
5) City/area has shown willingness to work with the NFL.

Cities bid on it and the team owners vote on which city to choose

Because it is the most southern weather of the major cities.

It's a good weather location with a lot for fans to do leading up to the game.