Another place not to be missed if travelling in Iceland (or Copenhagen for that matter) with children is the Laudromat Café. I like the nice interior and the large playroom downstairs where you can also wash your clothes. It's always very busy so it's a good way to meet locals, especially if you bring your kids. I haven't been 100% lucky with the food and the service. But they have great coffee. And the playroom is to die for although coffee is only allowed in the doorway. Hope you have a nice weekend!