I remember having a lot of fun in Morrowind making homes in the editor using the sectional interior pieces, and went to do the same thing for Oblivion. However, I can't seem to find any sectional interior pieces to really build a 'custom' home that isn't a dungeon. Are all the houses in the game really just premade statics? I mean, yeah, it's neat that they all match the exteriors but I'd be willing to suspend my disbelief for an actual custom home I don't have to make in blender. Am I just overlooking something?

Closest you're going to get is some of the middle and upper class Leyawiin interior pieces. Otherwise, you'll have to think outside the box. ha ha ha for a really custom home interior.

There are some resources linked on http://www.oblivionsrealestate.com/, but I do not know what the permits are on those. That is a good resource for house makers, however. You may want to try http://www.tesalliance.org/ as well.

This is a great resource: http://tesnexus.com/downloads/file.php?id=30181- don't be fooled by the name, there are windows included with this set, and it works well for general house interiors, not just basemants.

Also, http://tesnexus.com/downloads/file.php?id=29205 by Lady Li is a stylish IC tileset, as well as Jakhar's Pelagiad tileset, which I found here: http://www.oblivionsrealestate.com/Resources/Architecture/New_Models/new_models.html.