Whilst I wonder weak and weary a Midnight Hallow not so dreary?

I use the Midnight Hollow Default Terrain Replacement Mod by Shimrod. It really brightens up the world, even without using a lighting mod. I also use the Default Overrides for Midnight Hollow Plants and Trees by Aminovas. It lightens up many of the world's default plants.

If you're interested, try Googling those mods. I believe they're both hosted on sites that require registration (free). :)