I have to admit I have never heard of Duke's Mayo before. But, for those who do not like Miracle Whip, definitely use mayo. We all have our preference so tweek it so your taste buds are happy.
I did forget to add that I sometimes add some Craisins if I have them on hand. They add another unique flavor with the grapes & apple.
I am thrilled that so many of you like my recipe. I hope that some of you who try this recipe will come back and repost and tell me how you liked it. And, thimblebug 6000, So sorry to tell you, that I finished off the last of my chicken salad right before I posted this. But, wouldn't it be fun for a bunch of us to meet and share some of this chicken salad and a glass of iced tea, and get acquainted. May even want to do a little quilting together. LOL!!!!
ENJOY!