Plain salted peanuts are fine, but why stop there? For boiled peanuts, try a “Cajun bath”: add Cajun seasoning, fresh garlic, and a bay leaf to the boil. For roasted ones, dust with chili powder and lime zest after they come out of the oven.
I once added maple syrup and chipotle to a batch of roasted peanuts. The combo of sweet, smoky, and salty? Devastating. My friends ate them all in ten minutes and left me with a pile of empty shells. Rude, but a compliment.
How Long To Cook Peanuts In Shell at Marvin Goff blog