Well I'm not a leatherworker, nor have I ever played a shaman, so I am not sure what would be best for you. :) However, I play a hunter and it seems like a lot of the dragonscale armor has stats that would best benefit a hunter in that they have a lot of +sta and +attack power which I don't think are stats that benefit shamans.
If you want to know what patterns are available, there is a list of them all right here on the site: http://wow.allakhazam.com/db/skill.html?line=165
If you scroll down, you'll see the 3 types if leatherworking broken down. Actually, now that I look at the list, there may be things in dragonscale leatherworking that may benefit you. I just have never seen them before, maybe because they would only benefit shaman, which we don't have on the ally side yet. haha
Anyways, hope this helped a little. Maybe others who have played shaman will be able to give you more insight.