Potato salad is one of my favorites. I have a number of ways to make it, but DH prefers it simple, the way my mom made it. My dad and our relatives loved mom's potato salad--potatoes with just mayo, cucumbers, eggs, and parsley. Part of why it's so good is that we use only russets. Cooked perfectly, they add to the creaminess of the mayo and make it a bit thicker.
As long as they don't have onions, I'll eat just about any potato salad.
As for
tuna salad, I add just a bit of vinegar, mayo, black pepper, chopped apples, and pecans. Yum.