I have two suggestions on these. Overall, I like Soft 75.
As far as happy and friendly enough, I completely agree. My first suggestions is possible some kind of bloom effect and some objects of contrasting colors to fill some of the empty space. Lava cracks on the evil side or light colored flowers, tall grass, or plant life on the good side.
The other reason I think it looks gloomy is the fog of war. It looks like a haunted graveyard fog. Can you make this fog of war a little more friendly, or is the super mystery/fear factor of the darker, scarier fog intended? If not, I suggest looking at a game like Anno 1404: Dawn of Discovery. The colors are really vibrant and the environment is relaxing, even when corsair ships hunt you down. Their fog of war is light beige parchment color, with compasses and sea monsters and navigational lines on it. Here's a picture:
Perhaps if the fog of war was lightened up, too, you could add drifting, fluffy clouds (Or dark, stiletto clouds on the evil side).