The Rossio Hotel was suitable for our needs. The location is incredible—directly across the street from Rossio train station that brings you directly to Sintra in 40 minutes. Plenty of restaurants and shops nearby. The rooms are clean. The staff is generally friendly.
Our primary qualm is that the photos on Airbnb are not an accurate description of the room. The room was far smaller than advertised, and was a bit uncomfortable for two travelers over three days. There is also no patio or balcony as advertised. Even still, given that the positives outweighs the negatives, I would recommend staying here for two mid-20s traveler.