Its its just one cab, you probably will have too many games. Consider that someone who is good at a classic will take 10 minutes or more to get a single play in. I would figure 10 minutes for each game played, multiply by number of people and number of games you want to play.
With socializing, and whatnot, that should give you a fairly accurate representation of how long it will take. Divide that number by how many machines you will have up and running.
Also if you want to avoid ties, the way I did mine was top point getter is worth 5 points, everyone within 80% of that score gets (their Score)/(top score) x 5
When I ran mine, we played for about 6 hours. I had three phases of competition, head to head (fighting games), side by side (classics, aim for top score), and individual (skills challenge). I had 4 machines up and running, and about 12 people.
With that, ideally I would need to limit it to 3 fighting games, 4 classics, and 5 skill challenges. With that setup, people still wouldnt get a chance to play everything.
So anyway, I would be careful about how many games you set out to play. In my tournament, I ended up cutting out two classics and 4 skill challenges 2 hours into it, because I realized it was just too much stuff.