If you are all on the same package on the first trip, and only some of your party are going to come back on the second trip, your best plan would be to book your admission for what is best for the group. Sometime durring your (first) trip you can upgrade your ticket to an annual pass.
For example 6 people are going on a 7 day trip in June. Everyone on the package gets 7 day MYW passes. 3 of the people are planning on coming back later in the year. Those people go to guest services and upgrade their MYW tickets into annual passes. You will get full credit of the original value of your MYW tickets applied to your new annual pass.
If your not on a package, just get everybody the passes that best fit each individual.
The only exception to all of this is if you're going on your second trip durring the free dining promotion. In that case you might be better off just getting MYW passes for both trips. MYW passes are required as part of your package with the free dining. MYW passes are also required when you want the dining plan and are paying for it.
