Victory by Dominion
Victory Point (by # of Capitals)
Victory by Provinces

Any of those can be easily broken down into a Rating system and doesn't leave the Tournament in a lurch because of long drawn out games that take months to complete.

My guess would be an average game Lasts ~40 Turns based on the conditions and a long 'hard' game would end ~60.

But that is also determined by the map and by # of players on the map in question.