I don't want to hijack the thread, but yes, Russ, we will be looking for a house. We were looking at big box cookie cutter houses in a new development (not seriously, just for funsies) and I tell you, I'd be happy using one of the walk-in closets in those huge homes.
Most likely I'll be relegated to the garage or basement. One place had a detached garage and my wife's suggestion was to build a second story on the garage (if possible) and make that a guest apartment/train room with the workbench and shop downstairs. Basements can be soggy in this wet country...although today it is sunny and clear...go figure.
And nkp174, you're exactly right. How many monster layouts actually get finished? How many mid-sized layouts even get beyond the plywood stage? This is why I started small with a switching layout, with the planned layout for the current garage a 4'x6'. Managable, even if compromises must be made. Better a small, complete layout than a large, unmanagable and unfinished pile of lumber with track on it.