Great thread, Lanolin!
I have always loved living spaces, whether big or small, one room or 50 (I've only toured places that large, never actually stayed in one!) But if I had to choose something permanent, I would want something comfortable. Nothing too big or that too much time and expense to maintain. Just enough to have some room to move about and yet feel cozy when friends hopefully came to visit.
My dream residence would actually be everywhere. I've always wanted to have a "home base" where I could keep my things and come back to in order to recharge, but if I had my "dream life," I'd spend every couple months in a new location or dwelling. I would see what friends were available and say, "Hey, I found this great deal on such-and-such site, what would you think about going to X place and living in (a fort, a cottage, an igloo, a tree house...) for a week or however long we could stay?"
I've gone through small periods of my life where I had a taste of that lifestyle and would find myself in the middle of suburban America one month, in the middle of nowhere the next, and various places here and there like the top bunk of a friend's child's bunk bed, and I loved it all.
I love the expression that "Home is where you make it, and whomever you make it with (whether friends, family, or a spouse)," and someday, I would love to be able to test out that theory.