http://www.allearsnet.com/pl/breakeven.php
Not sure if this works for you, but sometimes an Annual Pass is less expensive than a hopper.
If you are staying on property, the Annual Pass discount available for the resorts might make the AP purchase worthwhile.
Good Luck!
From time to time some outlets including Ticketmania sell 8 day passes for less than 7 day (expiring) passes.
Making an 8 day pass non-expiring (for $107.) is highly not recommended unless you also add 9'th and 10'th days (for $4. each).
Making a 7 day pass non-expiring costs $59.
Nine, ten, and most eight day vacations are best done with expiring passes. The break even between standard passes with hopping and an annual pass is about 12 days.