Here's one I've never seen but wish I had. Let's start off with the inimicable Bernadette Peters losing her mind:
Follies is a musical with music and lyrics by Stephen Sondheim and a book by James Goldman. The story concerns a reunion in a crumbling Broadway theatre, scheduled for demolition, of the past performers of the "Weismann's Follies," a musical revue (based on the Ziegfeld Follies), that played in that theatre between the World Wars. It focuses on two couples, Buddy and Sally Durant Plummer and Benjamin and Phyllis Rogers Stone, who are attending the reunion. Sally and Phyllis were showgirls in the Follies. Both couples are deeply unhappy with their marriages. Buddy, a traveling salesman, is having an affair with a girl on the road; Sally is still as much in love with Ben as she was years ago; and Ben is so self-absorbed that Phyllis feels emotionally abandoned. Several of the former showgirls perform their old numbers, sometimes accompanied by the ghosts of their former selves.http://en.wikipedia.org/...
The Broadway production opened on April 4, 1971, directed by Harold Prince and Michael Bennett, and with choreography by Bennett. The musical was nominated for eleven Tony Awards and won seven. The original production, which ultimately lost its entire investment, ran for 522 performances. The piece has enjoyed a number of major revivals, and several of its songs have become standards, including "Broadway Baby", "I'm Still Here", "Too Many Mornings", "Could I Leave You?", and "Losing My Mind".
Elaine Paige is "Still Here":
Elaine Stritch is a "Broadway Baby":
"Who's That Woman?" was a bit slow to load for me, but it's well worth it: