Let's take a look a gem hidden in Games Workshop's past - the Mighty Empires campaign system.
The set comes with 48 hard plastic interlocking tiles, most of which (all except the mountain tiles) are double sided. I recently painted these up and I think they came out quite awesome.
There are a variety of plains, woods, farms, wetlands, and mountain tiles. The tiles lock together pretty solidly, creating a fairly study 3D map that can be customized to your tastes.
Also included is a booklet outlining campaign rules for the system. Although the booklet is a good size, it's only actually five pages long and repeats the rules in six different languages.
Throughout the campaign, you conquer tiles. The campaign is split up into campaign turns. You take the average scores of all the games you played in the campaign turn (example, one week), and get a set amount of "Empire Points" based on how well you did. You can spend the Empire Points to conquer other tiles. Empty tiles cost more than occupied tiles, obviously. In order to take an occupied tile from another player, you must have beaten them in a game that campaign turn.
The included rules also have options for upgrading tiles with both castles, cities, and mines. You build upgrades by spending varying amounts of Empire Points.
The castle upgrade simply makes it harder for that tile to be conquered (the opposing player must spend more Empire Points to do so)
The city upgrade is an upgraded version of a castle and requires a castle before you can upgrade it. Think hotels vs houses in Monopoly. It provides the castle anti-conquering benefit and also makes the tile count as double when counting who has the largest empire.
Mines can only be placed on river riles and allow the tile to generate gold. Gold can then be used to purchase additional army points in a game you play. For example, if you're playing 2500 pt Warhammer Fantasy games in your campaign, you could spend a set amount of gold for an additional 250 points.
As you can see, the upgrades fit on the tiles and also have spots for the claiming parties flags.
While I don't play enough Warhammer Fantasy these days to warrant using this system for it, I do intend to adept it for an upcoming By Fire and Sword campaign. I've yet to iron out the details - one of the key points of the system for WFB is allowing you to take additional "points" in your army, but BFAS is designed to allow you play different points anyway! Watch this space for details once I finalize the BFAS campaign rules, and if you have any suggestions, feel free to toss them our way!