A Series of Trade Offs, Part 2: Adding on, up or out?

Continuing with our Series of Trade Offs, we move on to the decisions and trade offs that need to be discussed before adding on to your home.  Should you add a second story, add off the back or side of the house, or is there even unused spaced in the existing home you could use instead? Or, what if you didn’t add on at all…ever consider an elevator?