My experience has been that US immigration people at YVR pre-clearance give me more hassle than anywhere else I've experienced. For my next trip, I want to go through US immigration in the US.

I know there's a few US flights that don't go through pre-clearance in YVR - or at least, there used to be (YVR-HOU red-eye special comes to mind.. and I think there was an ATL one?).

Is this still the case? How do I otherwise tell before booking it if a flight goes through pre-clearance?