So let's be realistic. Barring being a place to drop those storage chests, housing is 99.7% about bragging rights and flaunting all the pretty things you have collected/crafted/bought/found/etc. And that's 100% okay. But another thing people like to show off are their outfits and motifs, as well as the characters themselves.
So basically... how cool would it be to have our characters be "placeable" in homes? ZOS has proven that 'placeable people' can be done, what with Pirharri, Nuzhimeh, & Tythis Andromo (or any of the "Assistants") existing. And while I can think of 1001 things that could be even cooler in that regard, I'd even take something basic.
Poses: characters could maintain idle poses from whatever personality you have assigned them (if applicable). Alternately, they could be assigned when they are "placed".
--Limits: obviously you'd be limited to whatever personalities you have earned or purchased.
Outfits: Similar to poses, this could just be taken from whatever outfit/costume you've currently assigned the character(s) in question, or you could assign them an outfit or costume when they were "placed".
--Limits: also fairly obvious, but you'd be limited to whatever costumes and outfit styles/slots you owned. Also a given.
General/Overall Limits: Obviously different-sized houses would limit how many characters could be placed. As fun as it might be to cram 17 alts into an inn room, it's easy to understand why that would need to be limited. lol.
Interactability: while it'd be cool to have them say generic NPC dialogue like "hail" or "yes?" or whatever, that'd just be a neat little bonus rather than something to be expected. Again, much like housing, having characters as "furnishings" would be mostly just to show them off, and would save many of us a dozen or more loading screens if we're showing off.
"But Zulera!" I can hear someone say, "why do you need to show off?"
because why not? The only gameplay use housing has is for those storage chests. The rest is to flaunt your goods and achievements. Why not be able to flaunt a few of your characters that you've no doubt poured all kinds of time and energy into perfecting their look, the same way you flaunt the houses you've put hours into furnishing and designing? It'd definitely also augment the roleplaying community (for better or for worse), so that's a bonus as well. Surely I can't be the only one who's ever thought of this.
...and I suppose regarding what happens if a character is a "furnishing" and you log in with that character... maybe it's just a paradox like all the Eazbis/Nuzhimehs/etc that are anywhere at any given time. I figure that's a minor issue at best.
TL;DR—let us have our alts as special furnishings, please?
Shortly after the formation of the Ebonheart Pact, a Nord woman was given a tour of the Tribunal Temple. When later asked about the experience, she seemed upset. Suffice to say, the Dunmer were not pleased to hear this, and thus they inquired further.
"Well," the Nord frowned, "the priests were very angry and unwelcoming. They kept shouting things at me like "you can't drink that mead in here!" and "somebody stop her, she's running naked!" and "we can't catch her; she's covered in grease!""