One thing you could do is to have one point for each sorority member who attends the founder's speech. With a bigger audience, there may be more interest in helping the philanthropy.

Week long events can be fun, but also can be very tiresome, as said above. However, if they are organized and the competitions are simple like you say, the excitement would stay up.

For the party and trivia night, if Thursday is the big party day, then why not have it on that night and move the dodge ball to Wednesday.

Oh and I would say tug of war would be awesome for a competition.

It all depends
 

My school is relatively small thus putting more pressure on my chapter to participate in these week long events. At Western each semester a fraternity does one week long event and its a blast. As long as another fraternity or sorority has not beat you to it, own it! :D

I know my school annually convinces a handfull of well liked proffessors into running a good old fashioned collection contest. Some years they did "put $ in the jar with the name of the prof you want to have to _____" and some years it was the prof with the least $ in their jar (get them in on fundraising). The winner/loser (depending on how you look at it) either kissed a goat in a very public forum, or some other big "sacrifice". It always weoked pretty well for us, but we too had a much cmaller campus than the one you're dealing with.

But, if you did something with the fraternities and sororities instead of teachers, for instance, the winners of each threw an all campus party on the quad with bbq and games, or all the members of the winning GLO would let the beneficiaries of the carity (especially if its a kids philanthropy) push them in a lake or pool fully chothed. Something along those lines.

I know I'm a bit late on the thread, but hey, there's always next year.