A lot of people have already said this but the more the merrier:
-Updated SS such as BM/Poh/True Poh
-Not a lot of people do PVP anymore so I don't really see a use for those in the premium tab
-Weekly gold chest would do wonders
-Costumes? Pets? It would be refreshing to see some costumes that haven't been in the game for a while brought back, so why not put them in the premium tab?
-I haven't seen this, and maybe it wouldn't make sense but Designer Thread? There's clothing merchants everywhere with hard to come by outfits because Designer Thread is rare. Just an idea.