Some attractions you don't need FastPasses for. I'm thinking Journey into Imagination and The Living Seas with Nemo ride at Future World at Epcot. You can reserve FPs for them, but why bother when you can often walk right on them? A great ride at Animal Kingdom, Dinosaur, seldom has a long wait--don't need a FP for that, either! In fact, two different times during my passholding local adventures at Walt Disney World, I have arrived at Animal Kingdom an hour before closing (when it used to close at 6PM), and rode all three rides in Dinoland--Dinosaur, Primeval Whirl, and Triceratops Spin all within that last hour. You may want to try that, and then do what another poster recommended--walk over to Pandora and see if you can get in the Flight of Passage line last minute.
Another waste of Fast Passes is shows like Mickey's Philharmagic (Magic Kingdom), or Voyage of the Little Mermaid (Disney's Hollywood Studios). Whether you have a Fast Pass or don't, everyone is let into the theater at the same time. An exception might be the outdoor ampitheater shows like Rivers of Light. Having a FastPass could perhaps land you a more decent spot to sit, but I've gotten seated in what I found decent showing up maybe a half hour ahead of time instead of an hour and having no Fast Pass.
The worst park to be in without FastPasses is Magic Kingdom. I usually plan my visits to the theme parks early in the week and then go on Saturday. But on days when I've had to change my plans for forgotten reasons, I sometimes walk aimlessly around Magic Kingdom looking for a short line (30 minutes or less), but every attraction seems to have 45 minute lines! Sometimes you have to bite the bullet and just wait in a long line, or end up disappointed in your day and how you didn't get on much of anything.
