Yeah, aside from those four, the only other ones I've read - both as used bookstore acquisitions as a 20-something, so with a more adult perspective - are An Acceptable Time, which I remember mostly because I liked the antagonist and wished he'd made better choices in the end (I always kind of wanted Yuletide fic about him); and The Arm of the Starfish, in which I found it very interesting to see L'Engle, obviously a Christian herself, trying to put herself in the position of a moral atheist, adding two and coming up with five. I give her points for trying, at least. (I think that was also the one in which the heroine was almost raped by her lesbian mentor...)