Reason # 10237 why I won't use Windows any longer unless otherwise forced to do so.

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One thing I've learned when it comes to making architectural mesh, though... draw out a quickie floor plan on paper (yep, with a pencil).

Start with big (but faint!) circles representing areas - living room, bedrooms, etc. move 'em around a bit until you find a comfy layout. Then, start roughing out the rooms from there. You'll get a good feel for whether or not it'll fit... once you get that down, then the fun begins - making it all look good. :)