As to the topic at hand, I display some loose, and keep my carded ones boxed away.
For the 25th line, I have all of the main retail releases carded or boxed, except for a few really, really bad repaints like the first Duke/CC Comic Pack and the first couple of Snake Eyes/Storm Shadow CPs, and I don't have a few of Wave 4 figures carded because I had them all in the 5-packs... Besides that, I'm missing maybe clear Wraith (which I want to find one day) and PDD or Roddy Piper (which I never want).
Currently, my loose figures are all over our guest bedroom because I unpacked them for a bit and have some laid out on the bed to organize, some on the shelves to display or photograph, and some laid out for customs, etc... but I'm about to have to box them back up as the girl is terribly pissed at me for "having toys all over the place."
My boxed items are in our storage unit, which is currently about 30% of the storage space. If we end up moving again and getting a house with a space big enough for me to display some of them in a "nerd cave" of sorts, I'll do that. Otherwise, I'm tempted to sell off some of them, as they just take up a lot of room and it's all sort of silly now to have so many just stored in boxes.
I only display Joes and a few Marvel Universe figures, and I've got a few MP Transformers out from time to time as interest permits, but I've got a bunch of TF Alternators and Marvel Legends boxed away as well.
It's questions like these that make me feel like an idiot and want to sell because I currently have no place to display my Preciouses.