I have an
annual pass. I also believe that Heather R. has an annual pass and Beatrice has a Florida seasonal pass. I don't know if anyone else on the Panel does.
For the past several years the annual pass has made sense for me simply on the basis of days spent at the parks. But as you suggest, there are many additional benefits. Most notably, there are sometimes hotel discount rates for annual passholders. Often, only one member of a party needs to be a passholder for the entire room to get the discounted price. Other benefits to passholders include discounts at some shops (though not many) in WDW. My biggest savings as a passholder have come in two places: tours and dining.
Many of the "behind the scenes" tours at WDW have a discounted price for annual passholders. I recently took the Backstage Magic tour. Prices can change, but in January 2008, this tour cost about $200. At the time I took the tour, passholders got 15% off. I've also gotten discounts on the Family Magic tour and the Behind the Seeds tour. If this is something you might do often, the savings can add up quickly.
Also, a real surprise benefit to being an annual passholder was my ability to purchase a Disney Dining Experience card. This card (which cost $65 in January 2008) is only available to Florida residents and to annual passholders. The purchase of one Dining Experience card entitles an entire party (of up to 10 people, I believe) to a discount of 20% on meals at most of the table service restaurants at WDW. When we go to WDW we mostly eat at table service restaurants. I just spent 8 days at WDW with a group of 7 people. Using the Dining Experience card, we saved several hundred dollars, (and that was just in a week). This savings alone more than covered the cost difference in upgrading to an annual pass and the fee for the Dining Experience card.
Let me know if you have other questions.