Dress it Up (Gourmet):
If you want to really veggie it up - add 2 stalks celery, diced (with onions/carrots), 1 cup cauliflower florets (with tomatoes), 1 cup green beans, cut into one inch slices (with parsley), and 1 cup broccoli florets (put in right at end - will cook in broth). And for even more variety, substitute one green pepper for one of the red peppers, and one yellow squash for one of the zucchini.
Dress it Down (Simpler):
Eliminate the kidney beans and the pasta shells for a strictly veggie soup.