Please can someone recommend some books on 'higher-level' (couldn't think of a better way to phrase...) books on GR? I've read over half of Wald (General Relativity) and I'm about to finish Carroll (Spacetime and Geometry). I didn't really enjoy reading Wald (sacrilege!), but I've really really enjoyed Spacetime and Geometry - I felt it was more modern, and almost like I was being lectured in the subject. For some reason, it didn't feel the same with Wald, most probably because I read Wald from a .pdf and Carroll from hardback.
I really enjoyed the Black Hole aspects of S&G, but I feel that I'm little weak on gravitational waves. I'd also like to see some more advanced differential geometry too, like spinors and tetrads (even though I don't know what they are yet, they sound important). If someone could recommend a book with the feel of Carroll but more advanced content, I'd be extremely grateful.
I feel the answer to my question is to go back and try Wald again, however I would like some other opinions!