Heightmap Generator for a City Generator

[GrumblingHive]

Hello, I'm working on a city(actually more like a big network of towns) generator. So, it starts off making a terrain, choosing places to live, connecting 'em all up and then putting in all the streets and buildings and wotnot. So, since the whole basis of the thing is the terrain, I'd appreciate some friendly advice/not at all friendly advice/ brutal criticism of some heightmaps that the terrain generator churned out. They're only 256 pixels square(not because anything larger takes bloody ages or anything like that, cough,cough), but you can probably get the idea. The goal is nice varied terrain preferably with a bunch of suitable locations for town building, but it'd be nice if the terrain conformed somewhat to reality and didn't upset the river police too much...