I would rate Elvisoncd.com as the best site ever when it comes to Elvis songs and shows on cd. So detailed and comprehensive with a fabulous team.
Keiths site is the best and most comprehensive when it comes to Elvis sessions and which takes are on which releases. Also soundboards, rehearsals, early live recordings and much more.
Thanks to Ernst Joergensen, Roger Semon and Erik Rasmussen for the great work. Keep the spirit alive !
Both "elvisoncd" and Keith Flynn's websites are reliable sources of discographical information, which I visit often.
But if you're "looking for a detailed Elvis discography", like the original poster, "elvisrecords.us" is the one, as it lists every record issued in the USA from Sun 209 up to the late 80s, including most, if not all, of the known variations for every release (inner sleeves, too !).