Breakfast can be enjoyed at your hotel if you are not much of a morning person.   The Panama Bakery (on Main, near Las Palmas) sells danishes that you can buy the night before and enjoy in your room if you are not a room service fan.   Most hotels offer a nice breakfast in their restaurants. 

If you are more adventurous, there are a lot of great restaurants that serve breakfast in town.  Mister A's is right across the street from the Inn at Mazatlan, and serves a generous breakfast (try the huevos rancheros).  It's full of locals enjoying breakfast before they head to work.  Heather's Place is located close to Pueblo Bonito Mazatlan (Across from Oceano Place) and serves a great breakfast as well. 

If you're looking for coffee, whether at breakfast or later in the day, head over to Simon's, a coffeeshop in Centro Historico, one block away from Plaza Machado.