The early planning.
Somehow, my dream home didn't come with any great location for a large tank. I finally decided that I could "shoe horn" a seven foot tank into my home office. I wanted an eight foot tank, but, it was not to be.
To maximize space in this room, I gave away my nice desk and file cabinet, replacing them with a computer hutch. The only other piece of furniture is a queen sized sofa sleeper allowing the room to also work as a guest room.
I used sketchup to convince my wife that it could work.