I use plain Greek yogurt as a chicken salad dressing. I like it much better than mayonnaise.
You can use Greek yogurt for almost any recipe that calls for mayonnaise and is not cooked. For a richer flavor, you can add a couple of tablespoons of mayo, but in general, Greek yogurt is almost a 1:1 substitute for mayo. Using Greek yogurt -- even the full-fat kind -- means the dip is already lower in fat and calories than mayonnaise.
You can keep the Greek theme with dill, lemon and cucumber and make a tzatziki dip, do a curry dip, a green onion dip, spinach dip, or anything else that appeals to you.