Other appropriate nice-to-haves that will add richness, depth and complexity and take your broth to the next level are things like: daikon radish, parsnips, turnips; mushrooms (shiitakes are great, but you could also use buttons or criminis, which are accessible just about everywhere); green onions, leeks, shallots; konbu or dashima, both dried kelp products, for flavor and body; katsuobushi, hon dashi, a little dash of fish sauce; a little mirin for sweetness...