For the 1/6 scale -- some are sitting/standing/kneeling around on various flat surfaces -- shelves, the doll stage, around the sewing machine, etc. I have a big shoe-hanger on the back of the door, and those pockets are a good size for them, too. And some (action figures with molded hair or unfinished) are in a plastic drawer thingie. My roommate keeps hers in boxes (usually two or three together in an action figure's original box) in a cabinet. (I also have a bunch of them -- mostly Mattel dolls that I don't do much with anymore -- in storage....) I also have a number of plastic drawer units for things like clothing and props and furniture, etc. for setting up the stage.
The 1/3 scale ones are harder to find room for -- I have a display/seating area in the living room, where they share a big rocker and side table, either sitting together on benches or in 1/3 scale chairs or with stands. I should move them, because that area is not protected from sunlight, but I don't have a lot of other options right now. The white-skin dolls tend to hang out on my dresser (either sitting or standing with support), the bedroom gets very little sun, and that's where the sewing machine is anyway, when I'm working on stuff. Their props and clothing are mostly in plastic bins, but I really need to organize them better -- their stuff takes up much more space.
I don't like to keep dolls in boxes, because you KNOW that just makes them neurotic... You've all seen
TOY STORY 2, right?
(Though right now two of my big dolls are still in boxes, because they're un-assembled and unfinished...)
Sometimes one of the small ones comes in to work with me, just to pose on my desk and look cute.... The Obitsus travel really well!