I've been doing alot of research and from what I can tell, if your staying at the campsites (not the cabins), there is absolutely no gain from booking a package deal. If you purchase everything separate, it should be the same price. It actually hinders you to book a package. For instance, if you book 7 nights and decide to leave on the 5th night, there is no penalty for doing so without a package. If you have a package, you will loose the extra 2 nights because they cannot break up the package. This info is straight from the reservations desk. So, why not just wait until you arrive to figure out which days to go and which days not to per individual.
The only disadvantage is that you will get paper tickets and not the pass type. However, if you add the tickets to your reservations prior to arrival, they will then issue you the pass type, just make sure they don't try to stiff you with a package.
If anyone knows anything different please inform me, I'm always looking for a better deal.