Sounds like you are going to have fun!
Haven't been to the Derby but assume you are talking about having different tournaments for different games.
If say playing a double elimination tournament for each game, then assigning points for how well you finish makes sense. If there is a tie in the end, then go to a playoff with a completely different game.
It really depends on how many people you have, how many tables and how much time.
My personal favorite is round-robin tournaments if you have few enough people and/or enough tables. That way everyone plays everyone else during each tournament. And, if you play multiple games per match (say a race to 2+), then everyone reports the number of games that they won and the person with the most games won becomes the winner.
For example, the last small round-robin tournament I had with friends was 6 people, 2 tables, 8-ball, race to 2 and it took 4 hrs. At all times 4 people playing and 2 not. Round robins take a lot more time than double elimination tournaments but everyone plays the same number of matches and (unless you have a power of 2 number of players -- that is, 4,8,16,...) nobody gets lucky and gets byes.
My main compter crashed yesterday so I don't have the link handy that I was using to generate round-robin tournament schedules. But, I just did a quick google search for (round robin tournament schedule builder) and lots of options popped up.
