The only extra flavor I prefer with a Diet Coke is Jim Beam. Unfortunately, JB is not one of the new DC flavors.

That being said Coca-Cola has added 4 new Diet Coke flavors -  Ginger Lime, Feisty Cherry, Zesty Blood Orange and Twisted Mango flavors. Perhaps Ginger Lime would pair nicely with Jim Beam? Do any of the new flavors appeal to you?