WIP: Future Earth, my campaign/novel map

[Xeviat]

Hello all. I'm the founder of the Campaign Builder's Guild (though it's run by Ishmayl and others). I've been working on my setting for many years now, a world I use as a setting my D&D games and my novels in progress. While I am writing a fantasy world, I am approaching its creation from as natural a process as possible.

The world my stories and games take place in is earth in the future; 50 million years in the future to give a rough estimate. I spent a good deal of time researching scientists' future projections of plate tectonics. Since there's no singular accepted path for continental movement (and apparently there are some who discount tectonics entirely; read the expanding earth theories), I was pretty free to move the continents as I felt looked well.

I've already read a good deal of map making tutorials on this site, and they helped me out greatly. RobA's tutorial on using GIMP helped me out especially, giving me a method for randomizing the coastlines to look organic (and even created some nice looking costal islands).

Now that I have an outline map, I'd like to see if I can find some help placing terrains and biomes in an organic fashion. I don't need things to be 100% perfect, but I'd like some guidance if anyone can give it. In addition to my outline map, I have a map with colored bands placed to show general rainfall (dry, semidry, semiwet, and wet). I'm under the impression that the wet areas (dark blue) will tend to be forests (tropical or temperate) generally, with semiwet (light blue) being more sparse. Semidry (green) will be grasslands, and dry (yellow) will be deserts.

Please, offer any help you can, be it advice, guidelines, or (I wish) an edited map with where you think the biomes should be. Thanks for any contributions.