Inquiring minds want to know.
Mine is a queen (and only one person sleeps in it currently…myself).
We have a custom made mattress that is somewhere between a twin and full. It’s for an antique rope bed that I’m assuming was made before mattress sizes were standardized. Two of us sleep on it, but we’re both small.
Queen, and I sleep solo most of the time. I’m not sure how I’d fare in terms of sharing with someone regularly as I tend to plant myself smack dab in the middle of it.
Cal king. My hubby is tall. It’s the first time in his life his feet don’t hang off the end. Of the bed!
King, occupied most nights by my wife and I, and our two dogs, 55 and 75lbs. Sometimes I wish it were larger.
Full. One person, mainly. Plenty of room. I’ve slept in everything from California Kings (water beds) down to a Twin XL at college (dorm) which was really a nice size for my taller friends. I suppose the residence halls decided that it was easier to standardize on the XL (to accommodate athletes perhaps?) rather than have to deal with sorting. Big list of Mattress dimensions.
Steven Wright - “My girlfriend has a Queen-size bed… I have a Court Jester size bed… It’s red and green, has bells on it … and the ends curl up.”
King Tempur-Pedic with minimal headboard. The spare room is a queen-sized day-bed. The RV rear area turns into a king size width wise, but not lengthwise.
Full.
One only.
Full. One person (me) sleeps on it. It’s plenty big enough, but oddly I only sleep on the left side.
King, best thing I’ve ever bought.
My two dogs have a queen-sized bed, and they graciously let me sleep on one side of it. They’re good doggies.
Cal King. My wife and I are both sprawlers.
King, but I never venture off my half, so I could be comfy on a twin if alone. The dog is not allowed on our bed, but I almost always have a cat plastered against me when I wake up.
The guest bed at my mom’s was a full (she’s since gotten a queen) and when we stayed there, my husband and I did not sleep well.
King.
The Lady sangfroid started us using separate (smaller) overlapping sheet sets and comforters a while back 'cuz she claimed I hoarded the covers too much at night. Apparently, I’m a ‘roller’. She claims that one fine night, I actually spun the entire bed set around myself in my sleep, cocoon-like, leaving her to wake uncovered and frozen whilst I lay comfortably bundled in the entire set of coverings.
I don’t recall - slept like a baby… 
Full. Anything larger wouldn’t fit in our house.
Queen. It’s me and 5 dogs, 2 cats. I still sometimes end up clinging to the edge…
Full, but I wish I had a Queen size. Memory foam mattress though, and I love it.
Ours take their half out of the middle.
Queen…yet I sleep alone…and, worse, I always tend to sleep on one side.
(The other side tends to be cluttered with books, comic-books, and an e-reader…)