The Dragorn Blood I found dropped fairly well from the researchers down the hall near the wos zoneline.
The Breastplate dropped for me in RS at the statue camp... 3rd mob in. Had 1 other rott in the next couple of hours.
The Gloves in NC I killed Murkglider stalkers for about 2 hours to get mine
The Boots.. well I'm camping the caves near Anguish and not having much luck.. about 4 hours in and no drop yet.
One suggestion is to make sure (if there is anyone else in zone) that you /ooc what you are looking for.
*edit* I did get the boots today. I had a cleric, shaman, druid and my boxed necro fooling around in the caves near Anguish.... it took about 2 hours but they did drop. (damn I can't remember what did drop it)