I had an idea at one point to do a board in 2 x 6 'slices'. I made a lost of several slices with the idea that while they wouldn't be perfectly geomorphic, there'd be several options.
Slices as follows:
City
City morphing to plains
plains
plans with river to desert
desert
desert to city
or something like that.

The idea is that I could then add in additional 'city' tiles as needed.
Another idea was to find a box of some sort of flooring tiles roughly 1 foot square. make a template for some guide, but each tile should have half a roadway (and sidewalk) on two edges, with the rest of the tile being a building or othe 'feature'. If a big group of friends got into a specific game, farm out a tile to everyone to make terrain-building easier.
Of course, for Heavy gear Blitz n-scale model train buildings are just about in scale, so I've ordered some of them.