For your son - how about the George RR Martin A Song of Ice & Fire series? Most of my flist seems to have read it and we are all obsessed with it.

Also, I am currently reading The Name of the Wind by Patrick Rothfuss, which is the first of a series, but the subsequent books have not been published yet. So far I like it a lot, but I have not yet finished the book. It was recommended to me by the same bookseller who turned me on to the Martin books though, so I expect it to be good.