This is by far the best coffee in Denver. I mean, these baristas are total pros and REALLY care about the quality of their coffee. You will get a latte or cappucino with amazing latte art. If you chat with some of the baristas, you will discover an encyclopedic knowledge of every aspect of coffee. Nothing in Denver comes close.
Mattina is a great little coffee shop. Their pastries are always fresh and tasty. Its usually pretty quiet and a good place to do some work. They people are friendly and a nice overall experience.
If your a real coffee wiz, then you should already know about this place. it kind of tucked back in cap Hill but I'd definitely recommend finding it if you want truly gourmet coffee.