I took a look at your track plan: it definitely needs some development (a lot of the curves look really really sharp, even for N scale, and you'll need more space if you want a yard) but it sounds like you have given some thought to industries and purpose: it looks like you're planning a city on the left-hand side, with a passenger station (and I assume industries) and a harbor on the lower right, with some open country in between and mountains in the background. One thing to consider is how this will all look when put together--it's easy to map out vast spaces on paper, but on the plywood (or foam, I suppose) things somehow shrink. One possible solution would be to put a backdrop or other scenic divider in the middle of the layout--the city on one side, the country/harbor on the other. That would create the impression of vast distance between the two regions, and give you more backdrop space. Like I said, the actual track planning is obviously in its earliest stages, but you've got a good basic idea for what you want to do with the layout...bonus points for including a local tram in the city!