Steel General: Thanks!
Gluhoded: I used a lot of references for the veg. and the fields. I stared at quite a few maps, to see how the tree lines were placed in between fields. And basically, I created a "tree" brush that put down scattered color, then used a pattern to fill in the so it gave it the tree texture. For the fields, I basically color sampled satellite images of farms from google maps, used different brushes to add some variation to the colors, then applied a couple distortion filters on it to give it a painted type look. Most of the techniques I'm using on this map have been done through trial and error while making the map itself... but when I'm done I'd be happy to make a tutorial for you guys if you'd like, to show how I did a few things..

Should have an update either tonight or tomorrow!