It worked out for us to buy APs for our family of 7 - we originally had 2 family trips planned for end June/July 2008 and mid June 2009.Our first trip for 14 nights, our second trip for 11 nights.
Then, unexpectedly, we decided that just the two of us would go in January, so we got a 3rd trip in on the AP!
I feel like we got our money's worth!