Many straight plays have roles that require little stage time:
Barefoot in the Park has the Telephone Man and the Delivery Man.
Arms and the Man has a random soldier only appearing at the beginning.
For musicals, in addition to the ones mentioned above, there is Linda in Wedding Singer, Charlie Cowell in The Music Man, and currently Chef Louis in Little Mermaid.
Grizabella is on stage more then mentioned, she appears in the opening Prologue, Grizabella the Glamour Cat and its reprise, the three performances of Memory, and Journey to the Heaviside Layer. I think she is there for Moments of Happiness but I can't remember.
I don't think FDR doubles in the ensemble of Annie, at least he didn't in the last two Equity tours, as I asked Allan Baker and Raymond Thorne that question. Cool thread!
Dean: Can I tell you something?
Lorraine: That depends on what it is.
Dean: I think you're really really pretty.
Lorraine: (after a pause) Ok, you can tell me that.