What's a good role for a Tank to multi-class?

For you hardcore endgamers, what off-job is most in-demand for tanks? Melee DPS, Range DPS, or Heals? I mean, say you're 2 tanking a dungeon, and you get to a fight that only needs one tank, what role is the 2nd tank expected to be able to switch into?

With the exception of enrage Turn 2 (healer), people are usually dropping a tank for a DPS. You'd be best served trying all 3 roles though so you can fit into any party comp.

DPS or Heals.

It really doesn't matter which. Either way, you're diversifying your bonds and learning a different class and playing through the perspective of DPS/Heals will only make you better at playing your main class.

As a tank main who can also DPS or heal, I'm usually required to DPS more than I'm asked to heal.

I leveled ACN, MNK, and PLD to have all four spots.

I have WAR/DRG at i90, PLD/BRD at i87,and what class did i learn the most from playing? My SCH. Because now i know how hard it really is to do some of the things. So i know more appropriately when i gotta hit CD's or when i can expect to receive less healing because of mechanics.

Besides that, melee DPS would be best to learn from. Doesn't take too long playing a MNK/DRG before you realize that they'll want you to do ur best keeping the rear and flank of the boss available to them. And they don't want to see the front either, it's gonna hurt.