I keep mine in a closet under the stairs. So far, I have my Rug Doctor Mighty Pro x3, Sanitaire SC886, Kirby Sentria and Royal 884 under there, along with a shelf with some cleaning supplies, my commercial mop and wringer, and a broom. My Heritage II Legend, Avalir and JCPenney (Hoover Convertible) will go into our unused foyer closet once they are finished, plus my wife's upcoming birthday present, a new Dyson Cinetic upright, just for her.
I may end up giving away the Sentria to a family member since the differences between the Sentria and Avalir are minimal, and I prefer the look of the Avalir if I had to choose. Even though we're a childless couple in our 2600 square foot house, I don't think I could pull off a full scale collection. I don't know how some of you do it! I never thought that I'd be collecting -- the Sentria find started it all back in January of this year. It's very tempting to go back to the Goodwills and other thrift stores.