Why I Like BOTH...
Like Jon-O, I voted "combo".
Why? Well, it's
soooooo much easier to knock the darned things onto the floor while working on the layout if they're running through your work area. That way, I don't have to stop what I'm doing, put things down, get up, walk all the way over to the other side of the layout JUST to pitch a train onto the floor. Why make things difficult?
Okay, enough about my innate clumsiness.

I like to work with trains running, and when purposely running trains, I enjoy switching. My kids want to watch them go around and around.
When more space permits, I would like to have a run-through line that passes over the top of the workbench...something like a shelf with a track or two, maybe a scenicked "shadow-box", or something so that while working on some tedious workbench chore, a train will pass by every now and then. Maybe even fancier, a photocell thingy could announce the arrival of said train with a whistle...
Am I way off topic? If so, I'm sorry, but this is something I've always thought about, and it does (kind of) fit into a continuous-run idea.
