What works best for a productive day for me would be a dinner-for-breakfast type breakfast. Steak and eggs, dim sum, a full European spread of smoked fish, pickled herring, sausages, charcuterie, cheese etc But I can never say no to local favourites such as dosas, Parisian croissant, scotch egg, a NY/Montreal bagel, steamed rice-noodle rolls from a hawker cart with hoisin and toasted sesame sauce, a shiao-bing or roti filled with beef or lamb, chives and egg from a hawker stand at the market.
I had the yummiest freshest made-to-order tacos at a beachside cafe in Belize once.