All of these are good ideas. Just depends on who you attract to your business. I happen to think Costco Muffins are good. Inexpensive and huge. I even sell some at our locations. Good quality and great prices. I also agree that you can't keep them past two days. If you have your own bakery thats even better YUM! However, there are a lot of small bakers that make great products. Hook up with them as much as possible. We just happen to have a couple of our coffee accounts that are bakeries and even though we don't distribute baked products, we do get them a lot of referrals from other espresso businesses.
Hey Octalpus, what kind of business are you opening and where are you located? It may be a good idea to work something simple first before you add on other things like food, i.e., sandwiches, etc. Unless you are the only game in town or have a lot of foot traffic it may be hard to serve that many items. In addition, if the espresso is going to be your draw, you don't want to confuse your customer and take away from the sales of your espresso.
Just a thought.