We stayed for a weekend at Ilias place in Thessaloniki. The location is perfect to explore the city by foot and it has everything you need for a few days, including a large terrace from which you can see the sea and have a nice view over the city. A lot of good restaurants are close by as well.
Communication with Ilias was perfect at all times and access to the apartment/ handover of keys was absolutely trouble-free.
We can highly recommend staying at Ilias place.