I didn’t have this problem in Brooklyn, because our house there was much more compact (2 stories, 2 rooms per floor). Our new house is modest in size, but it’s been added on to over the course of its 200-year-old history in a way that is totally charming — and totally maddening whenever I need a pen.
My fountain pens live near my desk (or they will, once the room has been finished), but I like to have other pens on hand when I need to, say, jot something down for the contractor, or take note of a random idea. I don’t have this problem with notebooks, perhaps because I’ve accumulated so many over the course of our six-year history! So I’ve ordered a box of Pilot G2s to distribute throughout the house. We’ll see if that helps… or if they’ll continue to accumulate in random rooms and/or under the couch.
Do you have trouble keeping track of your pens?