I have one bass out on a stand for practice, a few nearby in gig bags that I use regularly and the rest in hard cases in the closet and under the bed. No need to keep them all on display. The strings will get oxidized, dust and general air pollution take their toll on anything in my place. I don't have a nice climate controlled basement or similar, and the Ocean is 10 minutes away, so that makes anything left out a bit crusty after a few years.