We were a bit disappointed with our stay at Ariston. We knew that Costco trips uses this hotel, so we thought it would be a safe bet to stay here.
The Expedia check in says that it begins at 1:30pm, but the hotel told us when we arrived that it does not start until 2pm. Our room was not ready until about 2:45pm. They did offer free luggage storage when we were unable to get into our room.
Our room did not have working AC. The hallway and lobby seemed much cooler than our room. After having hotel staff come into our room twice that evening, they were able to provide an oscillator fan. We were not offered compensation or another offer for the broken AC and were going to have maintenance review our day of check out.
The room had one wall outlet (later found one in the wardrobe) that was partially controlled by the wall switch. Therefore, our fan took the plug overnight while our phones could not charge.
We did get the breakfast and were disappointed with the "sweet" breakfast (pastries) which were a little hard and tasteless. The "savory" breakfast (eggs, meats, etc) looked better. Coffee was fine.
The hotel is a very short walk (1 block) from Roma Termini, which is great to train/metro to other parts of Rome, Italy, airport. It is a 50 minute walk to the Vatican, 25 minute to the Coliseum, 30 minute walk to Pantheon, and 15 minutes to Trevi Fountain.
Overall, the quality was a little lower than expected for what we paid for our evening.