Here are two table concepts that I have been pondering. This would be a pretty simple, temperate style environment to suite lots of different game types. The idea is that additional terrain can be used to create a more specific sense of place.
This table would be two parts, with each half containing part of a large hill for king on the hill games, or representing something of a valley.
This is the river table. Large terrain pieces set over part of the river could help the river from dominating the entire board.
Each of these tables is designed to have other sections added to them to increase size, and to flip around to create different layouts.
The hills would be stepped and would cover a large area of the table, but not all of it generally. The river would be a lot of fun, but I think the key to making it playable without being a giant pain in the ass is to create several fords in addition to bridge terrain that can be used to cross the river.