King, shared with Nashiitashii and the dogs. Dogs bloody well do count when they are large like ours. Both are in the 50-60 lb range and occasionally share the bed. I like my space, thank you.
King, alone, one cat (Maggie won’t let Turk up on the bed).
We’re working on the sharing issue but she’s not cooperating. :dubious:
King, alone. First we got one of those Sleep Number beds, which was murder on my back. So we took it back and said that we DIDN’T love it, not at all, and we got a king and a full. We’d planned to put the full in the guest room, and sleep on the king, but it turned out that my back loved the king, but my husband found it to be too hard. So he slept on the full while we looked for another king, and we found that we sleep much, much better in separate rooms.
I generally have a dozen books/graphic novels on the other side of my bed. He has cats.
King, alone.
I had a queen, but Ikea had these great matresses on sale, and I needed a new one, except they only had King size, so I bought one and dropped it on top of the queen frame. Shared with at least one large dog, sometimes two if they both want to sleep there.
It does not fit in my room. I have a bed, a night table, and just enough room to get into the bed and pile books and laundry around it. Dressers are in a different room. It’s the Master bedroom in the house, and might be big enough to hold a double.
I sleep alone on a 6’ x 18" floormat.
CA King, shared with husband. I liked our queen, but he really likes to sprawl out.
Full/double/whichever, alone. Except for the cat, who takes up a surprising amount of space for an eight-pound creature.
I live in a small studio cabin and anything bigger would be way too big. But a twin would make me feel like a kid. With this one, should I have company, there’s enough room, and it doesn’t take up half my floor space, and I don’t feel like a kid.
Queen. Sleep with my husband. It’s enough room for both of us and the dog at the foot of the bed.
First time I’ve heard this term, and I can’t stop laughing. 
Ca King shared, here. We have a long body-pillow down the middle, and he’s a big guy, and there’s still enough room. Which is good!
Wow. I appear to be the only one using a “full” (what I would call a “double”) mattress, shared.
Mind you, my partner is a small woman, so there’s plenty of room for both of us…
Full, alone. It’s an antique four-poster that was probably the equivalent of today’s queen before Americans started expanding. That being said, I know it’s technically a “double” but I can’t imagine fitting two people in it. And I’m a small, skinny person. Maybe it’s because I sleep kind of at a diagonal.
We share a queen, along with 100 pounds of canine. I would love a king size, but there would be no room in there for anything else.
Full, alone. Technically. No other people, that is. If it weren’t for the cat, I’d be happy with a twin (and I managed for years), but things get a little cramped in a twin with a cat who can stretch to be 2 feet long (and is usually perpendicular to the long axis of the bed) when she sleeps. Of course, now that I have a full, the cat doesn’t sleep with me as often as she used to. That’s cats for you. :smack:
I can sleep on a full alone, or a queen shared. And even in the latter, my legs may hang off.
And I’m only 6’3". I don’t know how actual tall people cope.
Twin, me and my cat.
I have a great comfortable queen size bed. But sleep on the couch with a bag of cheezies under my arm.
Bachelor in me I suppose.
King, shared . . . not only with my 6’10" partner, but also two cats and sometimes two dogs.
Full size is fine for a single person. I sleep on a Queen, because I got it when I had a girlfriend. When I replace it, even if I’m still single, I’ll get another Queen.
Because I’m an optimist, that’s why! 
Pro tip: Mattresses are bendy and easy to squeeze though doorways. Box springs are not. Next time you buy a bed (Queen or bigger), ask for split box springs. It’s usually a very minor expense. The money is all in the mattress. You will thank me 1000 times if you ever move your bed anywhere.