All DLC’s have separate storylines that you can play without completeing the main story. They refer to the main story in dialogue, so there are some spoilers here and there. That’s obviously not a problem in your case, since you’re at lvl 67. They all contain really great guns and gear, so you should definetly do them all to get your hands on those items.
Pirate dlc - Pimpernel (sniper) and Sandhawk (SMG) are both quest rewards and are the best of their types. One of the raid bosses, Hyperius, has a chance to drop the Norfleet (Launcher)
Torgue dlc - Farm Torgue tokens and then farm the Torgue vending machines for a DPUH (Pistol)
Hammerlock dlc - Chance to get the Rough Rider (shield) and the raid boss, Voracidous, has a chance to drop the Interfacer (shotgun)
Tiny Tina dlc - Antagonist and Blockade (both shields) and Grog Nozzle (pistol)
The Headhunter packs also offer some easy farming for legendaries, but those are random.
Apart from all those items, which are all considered as top gear, there’s also a lot of fun in the storylines. I probably missed some of the items, but those items alone makes it all worth the effort.