Sorry for the brief update last time, I was really tired.
I never really intended for the flat lime-jello-green and ambiguous-grey to be what I used for the walls and ceiling. It was supposed to be more like a placeholder until I came up with some decent tiles for them. Heh. Anyway, so here's what I'm trying out now:

Looking more and more like a house!

I also mocked up some lighting effects for the sconces. Hopefully that helps a little bit with their readability. However, I was going for an insectoid look to them (I'd like for some of them to be monsters in disguise, who could attack characters that get too close) and "praying mantis with a candle for a head" was exactly what I was thinking.
I was going to do a portrait of great-uncle Horace but I haven't designed him yet. I'll get on that, though. Glowing eyes optional? ;P
Haaands! I forgot to mention those. I added some (though not as good as Facet's, unfortunately) to the previous mockup. I would much rather redraw every portrait, but I have a fair few characters and I'd like to save a little time. (Plus, having interchangeable parts for the faces makes it easier to write in new scenes on the fly without having to stop and draw a new portrait if so-and-so doesn't have a "laughing" face, because most expressions can be made with a few different eyebrow positions and a few different mouths.)
Corinthian Baby:
I agree about the floor shadows. I have to admit; it's a bit of a short cut, but the other reason I'm doing them like that is to give the shadow monsters a place to hide. I'm looking at different ways to do the shadows, though, so I'll keep your advice in mind.

I have to admit that I initially tried to go for a darker, grittier style and... well, it's just not my thing. Too many games are dark and gritty these days! I will have color! Lots of it! Bright and shiny! I am thinking that I would like to have some sort of darkness overlay that is cleared by light sources.
I thought about the character perspective and I think I'm going to keep the side-on view. I know it's not technically correct, but I feel like you see more of the character that way.