use blocks for walls, floors and the ceiling. use models for everythign else. every stone every pillar everything else, use models...

sine models are noth lighted the way blocks are, you have to work around the colors of the skin when you have colored lights...

an example:

i have a level with brown colored lights, everything looks dark and muddy. i have statues in the level wtih a grey skin. howeer, they dont look muddy obviously since theyre not lighted the ay blocks are. so i just paint their skin brown (i chose the right color from a screenshot of a grey block thats lit by the light, so i get a perfect match) and voila: looks perfect^^

use models wherever you can and blocks just for floor and stuff. you can also add shaders to models but not to blocks...