Imagine a standard "go get my sister from those trolls" quest. In Oblivion you'd approach a random person and ask them about their sister without actually knowing that she's missing. You'd then get the quest, go get her and get a reward.

How about not knowing about the quest at all, stumble upon the trolls, kill them and save the sister anyway? She'd then tell you how awesome you are and you should go see this or that person for a reward. You could however kill her and tell her brother that the trolls did it.

If you accepted the quest from the brother (who should approach you and ask for help if you look strong enough for the task) you shouldn't have all the time in the world to do this quest. Accepting it, and then finishing the main quest in about two months time should not result in you still having time to save her. She should be dead by now, or rescued by the fighter's guild.

In a quest where you might find the quest giver's lost armor, you should be able to end the quest or hide it, if you find the armor to be good for you. However you should still be able return it later, but the quest giver's reaction should not be the same as if you'd focus on that quest and return it immediately.

What do you guys think?