We will absolutely stay at Iberostar Las Letras Gran Via next time we're in Madrid. Our corner room on the 6th floor had lovely views, and our 2-level unit (bathroom on entry level, bed/sofa sitting area upstairs) was clean, pleasant and decently appointed. The room decor wasn't particularly fancy, but we were very comfortable (and we don't need fancy). The hotel's "attic" level outdoor deck was excellent and uncrowded- we had wine up there a few evenings and loved it!
Although we expected the room to be noisy given the pedestrian and car traffic below, it was utterly quiet (only sirens pierced the quiet). Given this and the super comfy bed, we slept well all 5 nights.
Excellent stay- thanks so much.