Tackling the surface environment

Game environments are particularly challenging, especially when I hope to make them random.  I have already talked about the three levels of caves, and how I hope to randomize the cave system to be unique for every hexfield in the game.  The part that I am now concentrating on is the surface level from 60 meters to 100 meters.  To help illustrate what I plan to do for this I have made a simple diagram.

As you can see, a set of equilateral triangles can be skewed to fit the standard square tessellation pattern.  This means that I would be able to translate a standard height map to this field.  If I divide the surface area of the hexfield like this:

 I can then create a surface that is reflected in triblocks.  While it is true that some of the more unique facets of a triangular tessellation will not be reflected in this type of initial setup, players will be able to add blocks to this environment utilizing the full spectrum of possibilities.  The height map will need to have area's that are flat where bases can be created as well as guaranteed low areas that could intersect with cave levels.  In order to still keep the sense of randomness each area could be taken randomly from one giant height map.