If you want to treat yourself to something nice, have dinner at Huerto de Juan Ranas, located just below the San Nicolás viewpoint and with the best views of the Alhambra. It might look like a tourist trap, but it's a classic restaurant, somewhat updated, and has excellent food. The menu is limited. We recommend the "berenjena" (eggplant) in honey and the meat dishes. Dinner will run you about 40? per person with red wine. Reservations are recommended (958 28 69 25). Opens Monday-Sunday at 20:00.
If you want something less pricey, try Casa Torcuato, on Calle Pages. For 1.50? per draft beer, they give you very high quality tapas (marinated dogfish, cold meats...). If you prefer ordering by the plate, we recommend the fried fish (12-20? depending on the size), the gazpacho (2.40?), or the "San Jacobo" (12?), a slice of cheese between 2 slices of cooked ham, which is breaded and then fried.