I had a thought for how to use the cities in a touring rock band sort of way. The general idea would be to visit each city and collect as many fans (Kiss Army members) as possible before switching cities. There would be a minimum requirement that would increase as the "tour" progressed. After all cities were completed, there should be a "farewell tour" multiball with a dedicated song or something that signifies the completion. Here how I would see this working;
1) choose the first city at game start
2) collect X number of fans every time the KISS and ARMY grids are complete. The KISS and ARMY combos would be somekind of mulitplier/adder. The hurry-ups would also be some kind of multiplier/adder
3) When the minimum number is reached then the backstage pass lights up. Hit the scoop (or on start of the next ball) and pick the next city. Fan collection would increase until the scoop is hit or the start of the next ball.
I think this way of doing it has a few advantages; requires nothing new on the playfield, does not affect any of the other achievements or flow of the game, and it adds a separate "tour" achievement in the mix. When I play I rarely pay attention to the KISS ARMY targets, combos or hurry-ups, so it would give them a real purpose.
-Rob