Gardening. Nothing more need be said.
I also fear I'm on the cusp of being an armchair modeler
On the odd occasion that I have been through der room, I've mostly pondered the possibilities of layouts. Here is a rough plan of the size and shape of the room.
There are 2 4' bookcases on the right and bottom walls, and the modeling desk in the bottom right corner. the left side could be used for a fiddle yard.
Now some of you will be thinking 'build a lifting section and have a roundy layout'. I just don't think it would be interesting enough (and my woodworking skills would not be up to it). My thinking is a terminal (of some sort) on the top wall, and a through station on the bottom wall. The plan is to build MMW modules and use 600mm as the minimum radius.
In another left field thought, I'm not planning to base it on any particular prototype, but use bits that I visually like.