The following flavors are among the most compatible with pistachios:
Chocolate (dark, milk or white)
Citrus: orange, blood orange, lemon, Meyer lemon
Candied orange
Orange blossom water and rose water
Wildflower or orange blossom honey
Dried fruits: dates, apricots, raisins
Spices: saffron, cardamom, clove, sea salt, pink peppercorns