We are a family of 5 with 3 kids 13, 11, 8
We have 6 TV's
Fam Rm: HD LCD w/ HD DVR box
Our bedroom: HD LCD w/HD box
Basement: older tv digital box
Son #1: older tv digital box
Son #2: older tv digital box
Daughter: HD LCD w/digital box
We switched from Directv to cable (RCN) about 8 months ago. RCN REQUIRES that you have some sort of box (digital or HD) to get ANY channels since they now broadcast in digital. So, no more just plugging a cable into a tv...you get nothing, nada.
We were used to this with Directv. We had boxes on all our TV's, even the kids because otherwise you get snow.
So, it wasn't a really big deal to us to get the digital boxes. Some of our neighbors were quite annoyed however. Some of them had only one box in the family room and now they had to get one for every TV or see snow.
I should add that DH and I are both quite addicted to TV and both grew up in households with lots of them! We have a 40 inch LCD TV in our bedroom with an HD box if that gives you any indication. We bought if for our family room and both instantly decided it was way too small and bought a 53 or 54 inch (not sure) for the family room.