Standing outside Undercity late one evening, my little Forsaken warlock decides to poke around the surface ruins for the first time in ages, and there it is, an NPC with a quest arrow just standing there like it has been waiting for weeks. Turns out I had wandered straight past the entire Ruins of Lordaeron chain because I got distracted chasing a completely different quest trail and never looped back. That is the tell for me now, when a zone feels emptier of yellow markers than it should, I go stand near the dungeon entrance itself and just look around slowly instead of trusting my memory.
The trick that saves me every time is picking up dungeon chains the moment I am in the right level range rather than waiting until I feel ready, because by the time I feel ready I have usually already wandered off somewhere else entirely. Alcaz Prison is an easy one to miss too since it is tucked away on its own island, so I always make a point of sailing out there early once I am roughly in that level range instead of assuming a quest giver will chase me down.
Has anyone else got a dungeon they keep forgetting exists until they are ten levels past it and have to decide whether it is even worth going back?