Yeah- I think it's easier to have the A-B sequence be epic and not feel like a railroad... but it can pop up in smaller ways... Something we were talking about in another thread about meaningful choice basically meaning consequences...
So PCs know a Dragon is attacking... Defeating the dragon will be much easier with the Dragonlance, but the time it will take the PCs to get the lance is time the Dragon has to keep burninatin stuff and eatin dudes.
Well honestly, looking at it, certain things pop up.
The easiest way to think of it is that in most situtaions where there's a choice, there are a few option themes.
1a) Quick, dirty and negative. This is the "Means to the End" option. It's either morally ambiguous or just harsh. The old "seal the town and burn it down to make sure all the plague-carrying zombies and those infected are taken care of."
OR
1b) Quick, suspicious, and potentially negative. This is the "making the deal with the devil" type situation. It's not harsh. It might come back to bite the PCs on the butt. Or it might simply be allowing something Bad to happen while the PCs get what they need.
2) Good, but a setback. This is the one that avoids #1, but it comes with a price. Usually it's either "Time" "Severe risk to the self" "Loss of resource" or "Putting others in danger".
3) Do not act. Move on. That can mean a morally ambiguous/gray choice.
There are more than these, but they are often variations. Like "Who do you side with in this conflict?"
As many are saying, PCs can come up with option Z. But ultimately, what you are doing is presenting a Situation where the PCs must make a choice.
Pre-scripted results/choices are not necessary,
but the players must do SOMETHING. "There's a riot outside." That is something that requires some sort of response - any response IS a response, but it's one that the players react to.
So the real crux of the matter is creating a situation where the response matters, regardless of the response. Choosing a door doesn't matter. How the PCs respond to a situation that demands some response will.