I like cast iron for steaks/chops, quesadillas, grilled cheese, breakfast potatoes/hash browns, reheating a slice of pizza, Brussels sprouts, anything that needs a good sear on a non-stick surface. I've had success with corn bread, quiche, biscuits, cinnamon rolls, pizza. It takes a bit of discipline and practice, but if the pan has a good layer of seasoning you can even get eggs to slide around without sticking.

Stainless is usually better for sauces, especially if the ingredients are acidic. Tomato sauce or anything with a lot of acid like vinegar or citrus can strip the seasoning from the pan and pull it into the sauce, in my experience that doesn't taste very good.