Let potatoes marinate in the dressing for a few hours or overnight, refrigerated. When ready to pack for the picnic add chopped onion, chopped celery, sliced mushrooms and sliced or chopped Granny Smith apple. Toss well, adding a little more dressing if potatoes seem dry. Cut cooled chicken into cubes and toss with a little mayonnaise, chopped celery, chopped onion, salt and pepper. To basic chicken salad add cut up pieces of cantaloupe, mango, peaches, nectarines or apple.
Pineapple is a great addition.
Mix in a healthy pinch of tarragon and lots of freshly ground black-pepper. Chop a fresh jalapeno, if you like, and add that along with a little minced garlic. Fruit tends to water dressings down and make them soupy. It's a good idea to add a quarter cup or so of cooked rice. Serve the salad with wedges of pita bread.