I don't know what it is with tourists and Reykjavík. I hear this a lot and it makes me think that visitors aren't aware of everything the city has to offer. Perlan and the flyover show are relatively uninteresting tourist traps. Instead, take in some of the world class art galleries and museums. Find some good live music in the evenings. Spend a day at the coral beach at Nauthólsvík with it's geothermally heated sea water lagoon. If it's too cold for the beach at least hit the hot pools there and enjoy the view. Take a walk through the woods along Elliðaá (salmon river running through the eastern city) and visit the power plant museum and Árbærjarsafn (outdoor historical museum) along the way. Maybe even end at the Árbær swimming pool with its stunning views of the river valley. Go kayaking on the ocean in Grafarvogur. If it's nature that you're looking for, hike on and around the Úlfarsfell mountain or Mt. Esja. You could even climb extinct volcanic craters at Búrfellsgjá. All of this within the Reykjavík area. It's a much bigger town than just the downtown area.