get a wide variety of drinks and flavors, but you will also need some staples that most people buy like white mocha's, cappuccino's, mocha's, etc... Just so you know, a good professional espresso machine is pretty expensive. You'll want one with two groupheads/steam wands so you can handle all the business. Also you'll want to have some frozen drinks, lots of people love those. I think though that if you want to create a unique coffee shop and one that people will come to again and again, you need to provide them with some really good food. At the coffee shop i work at, we have soups, sandwiches, salads, and some deserts. We make all the sandwiches from scratch and grill them on panini grills. Our lunch menu has really kept the business going. Everyone seems to love them.

I've worked at 4 different coffee shops/cafe's in the past couple years so I know the ropes. If you need any more info, just let me know.