I just ordered 5-day park hopper pass for our June trip yesterday. Today DH announces that he may want to go back in Jan or Feb. Can I pay the difference and upgrade my park hoppers to Annual Passes? I sure wish he'd told me yesterday! Thanks.
When you arrive at WDW, all you have to do is take your unused passes to any Guest Relations window, and they'll scan them (to see if any days have been used) and give you credit toward an AP purchase.
Keep in mind that there are two kinds of APs. The ones that we have are the regular, no frills APs. This type will get you into the 4 parks- including park hopping (no hand stamp required) for the whole year. Includes parking and no black out dates.
The other (more expensive) type is the PAP (Premium Annual Pass). It includes the 4 parks, parking, water parks, Pleasure Island, Disney Quest & Wide World of Sports.
Here's a link with information and FAQs (Frequently Asked Questions). Good Luck!