Marcos Rooms is very well located in Oia, just steps off the main road. I think Panos lives in Athens while his parents run the B&B. Our room, A1, was right at the front, so we were awakened any time people were speaking outside our room, unfortunately--especially at 8am for breakfast. However, we loved Santorini & had a pleasant stay overall. We appreciated the free, filling breakfast served daily. The hosts were very generous but do not speak good English.
Major con: the shower. It's just a shower head in a bathroom--no doors, no curtains, so it soaks the room. Traditional old Greek house--but very wet, dirty, & inconvenient, especially since the hot water runs out after about 5 minutes. We dreaded showering every day.
In addition, the most negative part of our stay was the fact that the couple who runs the place yells at each other in Greek EVERY waking moment, & as the walls are very thin, we could hear it all the time. The woman absolutely screams at the man all day long, & it made us very sad. Obviously we could not tell what they were fighting about, but it was discouraging to us as we were trying to celebrate our 1-year anniversary.
For people on a tight budget or those looking for the feeling that you're staying in a traditional "Greek" home, this place is a fine idea, but I think next time we'll splurge & stay in a resort.