It might be cheaper for you to get an AP to cover those 16 days...so that you can take advantage of the DDP(I'm guessing you mean the free time-since DDP is always available with a package).
But any way what Mad4themouse is saying is each ressie only needs a 1 day ticket(regardless of length of stay-and as long as you don't use your room card at a park for admission, (you should be using the AP) you can save the single day tickets(3). You can either use them later on other trips or apply one at a time to a future trip's ticket(I believe-since they aren't activated). Also by doing the 1 day-as Mad4themouse said, each friend can upgrade for their length(without penalizing you)
I ran the numbers:
AP is 441.98 and 3-1day tickets are (63*3)189=630.98**(hopping)
3 trips-(7,4,5)ticket portion is 204,199,202=605.00**(NO Park hopping)
3 trips-(7,4,5)ticket portion is 236,233,234=703.00**(with Park hopping)
**apply the taxes, and the difference is a favor for the AP and 3 single day tickets(espically with the hopping)-but like I mentioned you can recoop the $189 later by using them for future trips or as a credit toward future tickets--one per ticket without having to pay for a no expiry. And is there any chance you might get another trip in within the year?. So I think the AP is cheaper.
++As an AP holder you qualify to purchase a DDE card (I think it is $85 now) but it gives you 20% off many sitdown dining locations- incase you are paying for items Off Card or more importantly for adult beverages
which are not included in the plan. And the card is also good for one year, and if you go on other trips-it is still valid too!!!!