How Many Trees Do You Put Up for the Holidays?

Now that we've moved past the "when do you decorate?" debate we can focus on a new one: how many trees do you put up in (or outside) of your house?

Growing up, we always had two trees in my house: one in the "family room" that we always used and my mom would put one up in the "formal" living room - that no one really saw but she'd go all out decorating anyway.

Since I've had my own place since college, I've always only done one tree. Until this year. I keep thinking we need a second small tree in our breezeway or one outside. I currently have my normal tree up...but I can't stop thinking about a second. Then I realized that most people I know do have more than one tree - especially if they have more than one sitting room or living area in their home.

How many trees do you put up and how many are too many?