i only got some ideas for a long term "yearly" tournament/championship:
every month 2 tables to play (classic / modern) + some specials like "battle of the originals"... so thats 24 tables per year
some exponentially scoring system: 1st - 100, 2dn - 80, 3rd - 60, ... down to 1 point for the 20-30th?
you have 3 winners every month: classic, modern & combined
and at the end of the year you have 2 champions & 1 grand-champion... and maybe 3 nice (virtual) pin-related prizes? and of course something "special" for the last

people can jump in/out whenever they want... if you can't compete 1-2 month you can still become champion
edit... more ideas:
tables should be mostly established & bug-free versions (newest releases are much played anyway)
next tables could be proposed during the month... and the "jury" could pick from those, or pick event-related tributes/specials for next month (what they think fits best)