We are going to WDW in two weeks. I have an AP, dd (12) will be getting a new one. The two of us will be returning to WDW in Oct for 5 days, and we are DVC so can get an AP for about $300. My dh's AP expired in August, and he didn't renew it since we didn't think he'd be going again within that year period. Well, things change...he is going again, but only for 3 days. An AP for him would have been $300, but I don't see him going again before June '07, so we got him a 10 day, non-expiring hopper. Yes, it cost more than our DVC AP but, he can use it whenever he needs it...he will still have 7 days on it, forever!
So, yes, there are a lot of instances where the 10 day, hopping non-exp. pass is a terrific idea.