I had a really small room when I was growing up, which meant I didn't have a lot of space to collect a bunch of clutter, so it was generally neat. I had posters and stuff on the walls, the bed, a night stand, a giant guitar amp and guitar on a stand and a stereo. Everything else was pretty much in the closet.
Now, many years (and crappy apartments later) I have a whole house that I've decorated. My bedroom looks like it was torn from the pages of Better Homes & Gardens (or the Pier 1 Import catalog ...) Since I've got other rooms, the bedroom can be relaxing without any clutter. I've got a "music room" now with about 800 or so records, 6000 or so CDs, 2 techniques 1200 turntables, a guitar, an amp, 5 or 6 pedals, a pile of cords, an ugly floor lamp, a media computer, a Nord keybord and a pile of framed art that we rotate around the house (and yes, a lot of the music stuff is my other half's).