I have other suggestions for different salads, but fussy eaters can be notorious for not liking anything new. I'll go ahead anyway for anyone who might be following.
Rice salads: I prefer to use Uncle Ben's for cold rice dishes for ease and predictability; I rarely use it for hot purposes, but like the separation of grains for cold salads. I either make them European, with an Italian-type dressing, or Asian, with rice wine vinegar, sesame oil, and lots of herbs. Tomatoes, cukes, peas, water chestnuts, onions, peppers, etc, depending on what folk like.
Near East brand taboule or couscous, rehydrated as instructions, then refrigerated. When cold, fluff with a couple of forks, adding scallions, other kinds of salad veggies, olive oil, chopped olives, pine nuts or slivered almonds (those bags of salad topping almonds are a great shortcut). My mom has a vegan friend, and this is one thing I used to bring when she had a picnic that was a rave.
If money isn't a big issue, and especially in the winter, cans of heart of palm, sliced, marinated artichoke hearts, liquid and all, onions, jar of pickled mushrooms, olives, and really, any pickled/preserved veggies, all tossed together with olive oil and some Greek or Italian seasoning. Top with crumbled feta or grated parm, asiago, or pecorino cheese (depending upon which seasoning you use).