The point of action points is to turn near misses into bare successes.
I recently made a table rule that when a player spends an action point, they get a little bonus XP if they describe the action in some suitably cinematic, heroic, or cool way. The side benefit is that it simultaneously allows me to add appropriate circumstance modifiers to their actions. I also let them know immediately after the action is resolved whether their APs made the difference between success and failure.
I've found they both value and use the APs a lot since implementing those changes.
-blarg