A more traditional take on this paella, from the region of Spain where the dish originated, would include rabbit and chicken, but this recipe only calls for easier-to-find chicken thighs. If you want, substitute 1 rabbit (3 1/2 pounds) cut into 2-inch chunks for half the chicken. If you can't find cranberry beans, double the limas.
A long, flat Italian cousin to string beans, Romano beans can be 6 inches-plus in length and as wide as two to three string beans. Because of their size, they cook equally as well on the grill or under the broiler as they do in boiling water. Find them at farmers' markets this time of year or occasionally in the freezer aisle.
Track down bomba rice at well-stocked supermarkets or check tienda.com or Amazon. (Medium-grain white rice makes a decent substitute.)