If you're visiting the Westfjords, the Heydalur Country Hotel was one of the most memorable stays I've had in a while. They often have a semi-tame Arctic fox on the property, depending on the season, as well as convenient hot springs.
I was fortunate to have my camera at the ready when this cheeky chap made a visit!
Closer to the beaten path, but if you are doing the golden circle tour, there is a geothermally powered greenhouse growing tomatoes on the way back just off the 35 road, Friðheimar Farm. They have a restaurant inside where they have the most incredible tomato-based dishes. Best Bloody Mary and tomato soup I've ever had in my life!