I'm currently challenging myself everytime I start a new world now to build a base that won't go defunct when Notch makes torches expire and replaces them wil lanterns.
The first design was a palace of lava that was built out of nothing but glass, lava, and some stone halfblocks for stairs leading up the central tower(A dangerous tower since the corners were pillars of lava so the ciruclar stairway had to have glass ramps added). I've since them put the project on hold because acquiring all the lava is taking forever.
My latest design however is just a giant pit dug from the grouind to the bottom to always be illuminated by normal light. Monsters that spawn too close will just meet a dirt wall they can't climb over, and spiders fall to their deaths. An improvement was made due to endermen where the pit is built in the ocean, and so is the underwater access.
So I guess my advice would be: creatively challenge yourself with your house beyond it just "keeping you safe". Try to implement something that will meet an extra need. You'll most likely force yourself out of that square mentality of yours that way.