I think Octavia Butler's Kindred could be an interesting one. A modern (well, 1976, when the novel was written) black American woman starts slipping into the past, into slavery times. Some interesting things happen (i.e., it's not just a 'wow. Slavery was bad. Let's feel good about how much better we are' spectacle.)
Lem's Solaris could be good too.
Every read or see anything and think it had good potential for a libretto?
I'd like to see more Nixon In China sort of nonfiction curveball.
Agree about Lem's Solaris! It can be great