Quoted from vireland:
The easiest way to get the cities into the game with the least amount of trouble is to assign a "groupie" or "STD" to each city that modifies the game a little (longer ball save, timed multiplier, spot starchild letters, mystery perk/bummer, etc). Hopefully they considered that.
Sort of like the paths in SW?
Very simple but yes, this would be a great idea.
Maybe reduce the number of cities to around 8.
Even simpler each city gives a note or two for each song.
Every city then has a purpose, without massively altering the game.