I think anything would be preferable to flour sticking to the outside of the loaf. So far I've only used sugar, and have done it with every quick bread loaf I've made that wasn't a savory loaf. Pumpkin, banana, cranberry, blueberry, nut breads, zucchini. I tried it once on onion since the onions were caramelized but I didn't care for it as much. Cheese bread I definitely didn't like it.
Seeds or grains sounds like a great idea, kicking myself for never thinking of that in all the time I've used sugar! I think I'm going to try a mixture of poppy seeds, chia seeds,& amaranth on my next onion loaf. I love the crunch of those seeds. Thanks for that tip!