The place is one of my neighborhood café shop, located in Vesturbærinn. It has really good sandwiches and the coffee is also good and on fair price, which I think is hard to get in Reykjavík. I often go there on weekends to buy sourdough bread (which is from Braud and co.) and cinnamon sweet roll with vanilla cream on top, its the best in town!
Perlan has been quite uninteresting for a while, but things has change and now Kaffitár has open a coffeehouse and restaurant called Út í bláinn on the top floor in the glass dome. The place is now mixed with different type of sitting eras, both for dining and for those who just want to sit down and enjoy the view with cup of coffee or glass of wine. The floor is full of cozy chairs and sofas surrounded with green plants. The place has by far the best view in town and I recommend to go there while the sunset bleed, its amazing.
Friðheimar is located in the south of Iceland just near by Reykholt (only 1.5 hours from Reykjavík). This is a fantastic place, a green house where you can sit down and have a local tomato soup surrounded by growing tomatoes and bumblebees. This place is a old family business that you can clearly see is run with a lot of passion. Almost every day you can see the owner running from table to table serving happy customers delicious soups. If you haven't been there, go because you are missing out!