I'm not usually one to seek out a tearjerker, but after working on a scene from Never Let Me Go in an acting class, my interest in the film was piqued. So I watched. Wow. It is rather bleak (why do almost all English films and television shows have this depressing grey-blue colour grading?) but ultimately fantastic.
Also, I would not recommend watching it while working out on the treadmill, as I did. By the end, I wasn't sure if I was covered with sweat or tears!