Hotel Attalos is a cheap little hotel in the Monastiraki section of Athens. When the air conditioning actually works, the place isn't bad. A rooftop bar overlooks much of Athens and, especially, the Acropolis, which is lit up at nighttime. The view from the roof is staggering. You can sit there with an Amstel beer and just gaze at the ancient wonder of the Parthenon.The location can't be beat. It's few minutes from the touristy Plaka district, or the Monistiraki metro stop, which takes you right to the port of Piraeus. The Athens Flea Market is also right around the corner.
Rooms are around $35 for a double with air conditioning (which wasn't working when I was there). The service is indeed very good and the men working at the desk are as professional as they get.
If you stay in Athens, especially during the summer, get a room with air conditioning. It's by all means worth the extra charge.