It should include any doors, closets, etc. complete with dimensions.  Is the entry on a 16' side or a 14' side?  Is the door in the corner or middle of a wall?  Can the door be blocked with a swing out or lift up bridge?

I'd put a return loop at each end... with a yard in one or both of them.... that gives you the option to run continuously, point to loop, or point to point.

This is one that I built for a no-longer existing BeNdTrack layout that illustrates the point...

And nix on the Torotise machines.... use 9g servos (as used in small RC planes, boats, and helis) controlled from an Arduino instead. You can put servos on 10 turnouts with an Arduino Nano for the cost of one Tortoise. It's a no-brainer. You can even make a touch panel for pennies....  literally,. You can make a capacitive touch switch with a penny.

Layout will be in the basement with only one access door. Open area with entry from bottom of the U.

Salvaged Tortoise machines from previous layout. Thanks for thoughts on loops at both ends. Was thinking single track with passing sidings in between both.

I don't want to derail the thread, but I'm intrigued by this reference. @barr_ceo, can you add a link or start another thread please?

And +1 for a return-loop at both ends, or a double-track main with loops at both ends (bent dogbone), and a yard at one end in the loop.

If you do a double-mainline, and connect the yard to both tracks, you can do out & back and turn the train you operate in the yard (while a second train runs around the dogbone endlessly simulating through traffic or just scratching the railfan itch).

If you don't design-in continuous running and later want it, you'll be unhappy with the layout. If you design it in and don't use it, it won't be a big deal as long as you also design-in some kind of point-to-point ability.

3 to 5 operators is a lot to fit into a 16x14 area.  Draw in that continuous run dogbone or loop-to-loop then fill the rest with switching-intensive industry and yards.  All sorts of possibilities in the industrial Midwest.

Scott Chatfield

+1 more for the option of continuous running: folded dog bone, return loops, etc. There can be a train running the "loop" while you handle the local switcher.

Starting a thread on the "touch switch for pennies" in my blog... we're gpnna learn about this together.

It's here now: https://model-railroad-hobbyist.com/node/37828

Don't expect a whole lot right away...  I wasn't planning on a blog post on this. ;)

 How wide can the benchwork be? Do you have room to make turn back blobs at the end of the U shape?  For 16' X 14'X 16' my first inclination would be a lift up or swing out section so I could convert the U shape to an around the room shape , then have the option of twice around to gain running distance.....DaveB