I read Cry, the Beloved Country back in HS and I thought it was outstanding. The description of a land "beautiful beyond the singing of it" from the introductory pages of the book has stuck with me ever since. Reading the book in a post-Apartheid world it may lose some of its urgency, but I very much liked the book.
The other books I liked from HS lit classes were Matamorphosis, ADITLO Ivan Denisovitch, 1984, Catcher in the Rye (which I had already read twice in grade school but still loved), Camus' the Stranger... that's about all that really stuck with me from the assigned novels.