Here in Portland we have shamelessly borrowed New York's SuperLeague format and made it our own (with some adjustments to make it better fit our needs.) You can see the full rules here:
Our major modification is you only play six machines a week (and some will repeat), and we added a finals. These were both concessions to the fact that POP HQ has less games than Modern Pinball and we still wanted to reach the 25 game threshold for WPPR purposes. We changed a couple other things but it is largely the same. Interested in people's feedback!
For POP, I think this serves a lot of purposes. Obviously it gets people in the door, and since we always have someone there to take scores, its not something that is easily repeatable in any of the other locations in town (largely bars.) Also, since we are all ages, it offers the opportunity for some of our younger players to get ranked and potentially qualify for state championships. We have one particularly talented 13 year old named Colin Urban who I think has a real shot at making it this year.
Thanks to the NYC crew for the inpiration!