I play a DK tank and we sadly do not have any sort of positioning ability at all. We do have a range-pulling one, which you mentioned (death grip, obviously), but it sadly does not work on many boss adds other than as an extra sort of taunt. A lot of boss adds are immune to the movement part, like the adds with Nef or Chogall, which puts me at a slight disadvantage on those fights. So, for example, if I'm kiting adds on Nef in the third phase (or whatever phase it is when Ony is dead and the lava has gone down), I have to taunt to get them off healers and such since there are multiple adds and depending on what runes are up I may not have enough ranged abilities to damage them for threat. On a fight like Nef when no one is actually dpsing the adds, taunting works great because it normally gives them enough time to get to me so I can hit them (with me moving to them as well, of course). Other fights may work differently, but I don't understand why you WOULDN'T taunt on most fights with adds and then start attacking them unless you knew you would need to taunt soon or something. They have such short cooldowns there's no real reason not to.

I guess I am just paranoid about saving taunts :)

I was just thinking that if the threat table's blank then FFF/Avenger's Shield/Heroic Leap/Feral charge gets you a bigger bump of initial threat to work with.

I know nothing about DKs though, so if you say taunting's the way to go then by all means, taunt away