I agree cold salads are a good way to go. I’d probably suggest doing just one mayo based salad and look at other salad options without mayo.
I personal love both cold sesame noodle salad and chicken salad so those ideas sound great to me.
Other things I make along this line are:
a couscous salad
a thai-ish chicken salad with pulled chicken on a bed of leaf lettuces mixed with mint, basil, cilantro and veggies like red peppers, cucumber tossed in a peanutty dressing
salad nicoise with fresh salmon cooked ahead of time instead of tuna with a lemony dressing
Cucumber salads are refreshing and I particularly like an asian influenced one with rice vinegar, cilantro, a little chilies for just a little kick.
I also make an orzo pasta salad with shrimp, dill, cuke, feta, a little red onion in a lemony dressing. I put grape tomatoes in it but you could set some aside before adding those.
I could suggest others but those are just some additional thoughts.
Roasted veggies are also nice done before and served room temperature.