Since I have been using DAZstudio a little, seems obvious that I would look at Bryce next in terms of the Landscape software. It seems to do the landscape generation, and trees and organics. At first glance it doesnt seem to have the depth or firepower of Vue - but does seem pretty capable none the less. It is very cheap though and just look at the images that it can make:
[images from the Bryce gallery on http://www.daz3d.com/i.x/galleries/0/-/? ]
A large part of DAZ's model for pricing is around selling content for its packages. The same goes for Bryce which has a slew of models to download http://www.daz3d.com/i.x/shop/catmain/-/?cat=106 .
OK so I had my own bash at using Bryce (free version 5 that came with my ImagineFX mag).
There is a tute in the mag as well for Bryce which gave me a few pointers - but it isnt quite as simple as it makes out. I havent got the hang of the editor yet - strange interface again that the DAZ software has - some nice things once you get used to them, but still weird.
This image took me quite a while actually and despite the preview seemed to require alot of trial and error from me.
[journeytime = 3 hours]