I personally would not have chosen enchanting for the main tank.
enchanting doesn't have any specialty items (enchanting only) that benifit a tank, those specialty items benifit a spell caster more than anything.

I would suggest blacksmithing because at level 400 you can add sockets to your bracers and your gloves and make belt buckles that add sockets to anyones belt.
not to mention that BS makes some wicked tank helm and shield as well as a very good spell casting mace ( and some good intermediate shields ) for your shaman.

as for the jc trinkets or the alchemy trinkets... they are good but not the best in the game.

for a purely money making perspective JC daily rewards is worth a pretty penny on the AH right now, not sure how much it will be worth in the future.
you can make some great JC rings and gems are always nice.

you need to get skinning/leatherworking on one of you shaman. the leatherworking mail gear has some awsome chest & feet gear for your mail wearer as well as a bracer +69 spell buff ( leatherworker only )