I was watching last night episode of "Family Ties" in a pilot episode that the theme song for the pilot was not the Johnny Mathis version. I'm a huge fan of Johnny Mathis and the show. The original version was done by Dennis Tufano and Mindy Sterling. I like the most common version by Johnny Mathis. That's the better one. Here is the original:
http://www.sitcomsonline.com/sounds/familyties1stseason-tufanosterling.mp3

According to the credits at the end of the pilot, the song was called "Us". That song was changed and became "Without Us".

You're right, although that version of the song with Dennis Tufano and Mindy Sterling wasn't used only for the pilot - it was used for the first half of season 1 (about a dozen episodes or so).