I'm a certifiable Sondheim freak (including getting on line at Lincoln Center at 3am back in the 80s for the Follies concert) and Being Alive and No one is Alone were the other two I thought about posting
Jen- Definitely go see the movie. I've seen the show twice (the original and the Central Park revival) and they did a very good job in keeping the feel of the show. (and surprise surprise, unlike the Les Mis movie they could all sing).
Speaking of movies- Last Five Years is worth seeing (its on pay per view channels) if you're in a place where you can handle a musical about a disintegrating marriage.