I have 12 vacuums, 2 of which are in another country, and 2 of which are in daily use by family members, so my "storage" collection numbers 8. I keep them in a disused bedroom, on shelves and on the top of bureaus. I have 2 large plastic "tote" boxes for all the attachments, divided into smaller boxes according to the vacuum they fit. The only attachment that doesn't fit into the box is the Electrolux PNI, which lays flat on the top of a long bureau.
As for the hoses, about half of them hang on two widely spaced garden hose hangers fixed to a beam in the basement; the other half are draped over the beam. I guess you could say my collection takes up most of a small room.