I think there is way too much rain forest's, almost every seed i make i can see a rainforest from the spawn, they should be "rarer"
And they certainly shouldn't be able to be found right next to snow-covered mountains.
If there's one thing that bugs me about Minecraft, it's the way that Biomes generate next to each other randomly with no respect to proper geography. Like a lush tropical rainforest that's in the middle of an arid desert, the arid desert being intersected by a snow biome. Just ain't right.