Likewise, I just agonised over with specialism to go with my tailor. Was this pointless and I wont actually have any use for that now? (I've not checked in Dalaran yet what the tailor trainers offer)
For Tailoring specialism it is back to dear old Shattrath. You choose Mooncloth/Shadoweave/Spellcloth like it was done in TBC and this continues to do its work in WotLK.
This meaning that when making the cloth of your speciality, you create 2 rather as one. Now unlike TBC the 'epic sets' of these cloths;
Ofcourse these cloths are used for more as just these recipes, but besides the embroids nothing BoP yet. So whatever you choose can be based on various things, but it doesn't matter as much as in TBC where you could not craft/wear a specific set without having the speciality.