I love pasta salads and they lend themselves well to creativity (or to what you happen to have in your fridge!) They are great fresh, but making them ahead helps the flavors marry. I've never used all these things at once, but experiment with what you like, but here are things I've tried in various combinations that are yummy:
Pasta-rigatoni, spaghetti, or corkscrew pastas work well. For more delicious alternatives try precooked tortelini or raviolis.
Meats-chicken, tuna, ham, linguicia, or turkey. Or go meatless!
Cheeses-I've used everything from cheddar & mozzarella (2 varieties always in my fridge) to speciality deli cheese like Dubliner, Feta, Parmesean, Romano & Bleu cheese.
Veggies-tomatoes, black or pimiento olives, scallions or red onions, finely chopped lettuce, shredded red cabbage, shredded carrot, bell peppers (use multiple colors for a prettier salad), cucumbers, or summer squash.
Sauces-you can go basic with vinegar & oil; vinegar, mayo & sugar; or you can use bottled dressings like Raspberry Vinagrette, Zesty Italian, Ranch or Thousand Island. Pesto makes a yummy salad "sauce" too!
Spices-spice mixes like Mrs. Dash and Salad Supreme are preseasoned, low in sodium, and a few shakes can really make a salad great! If you don't have any on hand, try sprinkling a little onion powder, basil, parsley & black pepper on your salad to taste.
How kids can help:
This is another dish that really lends itself to help of the kiddo variety. Kids can put veggies, meats, & cheese into the salad bowl & older kids can help wash & cut vegetables or shred cheese.