UMP (length of stay) passes are discounted 10% at the resorts. They include the water parks. We usually don't do the water parks, so they don't make sense for us. We have a DC card to get that discount for hoppers from the Disney Store for our guests. Because we usually plan 2 trips in one 365 day period, we always get annual passes for ourselves. Any time you will be "in the world" for more than 8 days a year, the AP is the way to go. The vouchers for these also qualify for the Disney CLub card discount.