Have you considered a zoom lens? I have a Nikon 18-105mm f3.5-5.6 zoom lens mounted on my D5100. I am very happy with it. I have the wide angle for most of the interior shots and it has that little bit of reach when you need it. I can't remember taking it off of the camera since I bought it in May 2013. I, like you, try to never use a flash and I have taken a lot of interior available light with really good results.
Please, don't keep us in suspense!