New to the hobby I suggest something small asap to run NOW while you ease into benchwork because this will take some time and effort. I always suggest a loop to keep you inspired. Some days you just want to unwind and run, not build.
Done right, on hardboard, foam, etc, scenery on the temp. layout can be moved to the big one as a module later too.
It doesn't matter if it's a carpet central or two old Craiglist coffee tables under the big one.
Asap, set up #1 a switching puzzle, #2 do full operations sessions, and 3# spend an evening looping and thinking about everything, or maybe thinking about nothing. What you expect to enjoy in the hobby isn't always what you actually enjoy. Some folk just want trains on a shelf, some folk want rare things, some folk run op.s, some folk toy around, some like toys some like scale models and others like me just can't decide on some things; but I'm more aware of my likes from experience, but these likes and dislikes have changed; evolved after more than half a century. There are things I enjoyed I grew out of, and things I snubbed as a kid I love now. How can you know except running? 🤔
I'm a looper first and foremost, bonus points for small logging, ore, and work trains but nothing beats passenger cars in a dark room, tunes and favorite beverge flowing; my indoor campfire
I don't mind distance runs. The loader/unloader job are ok too... switching to build trains or sort them is a pita though. I'm good at that type of organization but I get too involved, it becomes work and seriousness sets in vs relaxation... I'll have lunch while you switch then I'll pull the distance while you go to beans .
I like them, but I don't really use most of my accessories. #1 the loopers pal; AF automatic station stop #2 gantry & crane for rocket base (#175 I think), #3 operating yard crane
If you worked in a second reverse loop for each level you won't be forced to touch a train or back it through the reversing siding to go the other way, great for looping & operations both imo. (you can always close the second rev-siding with MOW during a session for an excuse for difficult backing )
More yard length lots of it, make the most of those switches.(railing stock gets old. the more side tracks in place the better).
You are gonna need hatches. Time to measure your reach. You do not want to have to climb; dismiss any willingness to climb you think you have. It is a pita and you will damage something eventually unless you are a ninja
....or Chuck Norris... sure he could do more damage than a ninja ( ), but the trains won't dare derail on Chuck