If you like good coffee and good wholesome food (breakfast and lunch) that isn't over priced or what I would call "wanky"/flashy, try out Mister Sunshines in Thebarton. A few of their barista's really know what they are doing and the food is excellent. It's getting quite trendy so avoid 9:30-11 rush.
The staff are super friendly and accommodating. And they use the De Groot Coffee Co. Beans from Port Elliot, which have a regular rotation in beans - usually South American.