My original team was with a Feral Druid tank, but I switched to Balance/Resto for raiding so I started a DK and now tank with it in Blood spec. I find it much easier (and more fun) than bear tanking.

My bear tank macro was:
/castsequence reset=combat Mangle (Bear), Swipe, Swipe, Swipe
/cast !Maul

I started out with one for trash and one with lacerate instead of swipe for bosses, but never had threat issues with swipe so just left it.

Pros:
- Health pool was higher (~50k vs my DK's 40k)
- AE taunt
- Didn't have to make sure I was defense capped


My DK tank macro is:
/castsequence reset=combat Icy Touch, Plague Strike, Pestilence, Death Strike, Heart Strike, Death Strike, Heart Strike, Heart Strike, Heart Strike, Heart Strike
/cast !Rune Strike

Pros:
- Death Grip is an AWESOME tool to have to pull casters in, one thing I hated as a bear tank. D&D is also great on pulls, and D&D+Pestilence is better AE threat AND damage than swipe.
- Heart strike hits 2 targets, so it's almost as good as the maul glyph.
- The extra healing from Death Strike is very nice for boxers. Mine currently heals for 5-6k every ~5 seconds. On bosses that don't hit too hard, it's enough to keep my tank healed without any direct healing.