I set a loop to loop on the floor of our TV/Bonus/Spare/Office/Art room several years ago just to test out some track designs. My intention was to build a layout in our walkup attic space. Eventually it was clear that what I wanted wouldn't fit where I was hoping so after several rearrangements and additions of loops, sidings, etc the floor layout is still in operation. Several sections have strong finished wood tunnels which protects track and equipment from feet and such., plus provide on track storage for equipment.
Structures are set on flats and are mostly stored on bookshelves except when doing lots of running. I enjoy watching trains work their way behind the TV console, under the desk, around the rocking chair, etc. On occasions I'll extend one siding out and down the hallway to the master bedroom to another large end loop which goes under the bed, past the closet, behind the sitting area, and back out to the hallway. This one is always for just one day to keep the wife happy. My support wiring stays in place since it runs tucked under the baseboards and kept out of sight by the carpet, the long loop is stored out of sight inside the hallway linen closet.
We have another unused small bedroom at the end of the hall that I might use to set up semi-permanent staging tracks, laying down the hallway connector as needed. Either that or build another N scale switching layout for which I still have lots of buildings and track. I really like to run long trains on large sweeping curves so the space required for an "O" permanent layout is just not possible.
I've also been working on some outside ground level modules for summertime that I can easily setup in a few hours for a garden type railroad, might get some stainless steel track and see if it survives the outside. Will probably need a "blower" car to clear debris and maybe a vacuum car to get the tiny stuff so it doesn't mess the locomotives. Inside I just use a handheld to collect dust and the occasional hair. The yard and staging would be setup in the garage and then a long,... long loop to the front yard, through the landscaping and back into the garage. I also bought a small RunCam2 4k camera that I attach on a car or locomotive to record the journey. My first attempt was using a small handheld video camera pushed on a flat car, but the quality wasn't good. I eventually used a rubber band and some extra weigh to attach my cell phone to a caboose, that worked but wouldn't fit through the tunnels and bridge structures. The view from the back as a long train winds it's way through the landscaping should be fun,..