When floorplans don't work, I often just work from pictures of the facade. I try to re-create them best I can in game and then fill in the rest of the house from my imagination.
It can also work to draw a floor plan on paper, that's what I used to do back in ts2.
By now I've built so many Victorian houses that I know the general lay out. If you like, you can check out my builds on the gallery and see if they inspire you. My gallery ID is the same as my forum username.