SAM as tank. Everyone played it as a DPS in XI when SE initially made it with a tank role in mind, but we didn't need another blood tank and ninja made a really really good evasion tank, so.... I think a mitigation based tank that buffs the party would be kind of fun - their own damage would be on par with PLD, but they can add damage boosts to others.
RDM as a sword wielding healer that can melee DPS too. I'd love to see something different, like an Encure spell that tosses a regen on any melee who attacks a mob (sort of like how DNC's indirect cures worked in XI). Give them a pure melee stance, kind of like Cleric's, that swaps out MND for STR so they can go full DPS whenever they want. Also give them an auto-attack trait that continues even through spell casts so the DPS is not totally hurt while tossing the occasional cure spell.
I'd also enjoy blue mage in it's XI form almost exactly. Although farming spells would be a pain!
