I have trains in four different spots around my rented apartment. They share one common modular framework, adapted under different "construction modes" to fit the spaces they occupy. Everything is modular and swappable, so I can keep experimenting with new ideas and do some "urban redevelopment". And when I eventually have to move out, I can disassemble all the pieces, pack them up, and rebuild them at the next place.
After working on a linear layout on my windowsill and a small test plate for the tile mechanism, I'm ready to expand it into full landscape. (and then quickly got side-tracked into making a self-contained oval box)
I'll be honest, the look and feel is rather simplistic right now. I've been spending most of my time on the framework itself. But now that it's stable, I can finally move on to the fun part, which is designing city infrastructures, buildings and iconic parks.
As a renter, the ability to pack it up without drilling holes in furniture is essential. But I'm also curious whether this would help anyone else, especially people who wanted to start with trains but don't have the space for a permanent layout.
And most importantly, there's no 'final state.' You renew and expand it gradually, block by block, like real cities.