The more the marrier!
My wife and I have four. One of the only things I dislike is the constant "honey the Plates are due". Here in Montana plates, forinstance on my '05 SRT will still run close to $400.00 per year.
Having multiple vehicles keeps them all fun to drive being you never get board.
Always keep a 2 seater in the garage, what ever it is for when your inlaws want to tag along. "love to have you ride with us but...?"
enjoy
Mike