I recently cooked the Rio Zappe beans with sauteed onions, garlic, bay leaf,
Mexican Oregano, fresh Thyme, in browned oxtails. I never soak them, they are fresh and cook up wonderfully in the slow cooker. Rancho Gordo has lots of recipes from their customers on their site, and you can bring them up from Google too.
Royal Corona, are not available right now, but they are my favorite. They cook up even bigger and each bean is like a mini baked potato. Great with smoked ham shanks, onions, garlic, bay leaves, a good meat stock in the slow cooker. They wrinkle up, get fatter, then cook up to a beautiful, heavenly, big bite bean, and they soak up the ham flavor beautifully. I like to cook my beans simple, so as to learn and enjoy each one for what it is. Later, I may expand into more complex dishes, but for now, it is all about the bean. Rancho Gordo are the best! Customer service is great!