Baseboards constructed at last! Here they are:

The key question is what to build here? Almost certainly this will be 00, because I've quite a lot of stock gathered over the years - though some is tatty and somewhat below par so will have to go!

So here's the overall plan:

(Red blobs are wall brackets)

No real track design yet, just a few placements to get some idea of what might fit in this space. Some sort of bridge structure on the dropped board, maybe built-up on the left, and more rural on the right leading to a fiddle yard? It would be nice to fit in a raised track at the back left to add vertical interest and scope for extra running.

All constructive thoughts welcome!