We stayed at Zachos together with my children aged 18, 15 and 4. We had a great time in Kea. The apartment was fine, and the view from the balcony amazing. Staying in Ioulida is a good way to explore the island (although you need a car and parking can be challenging in the peak season). The house is located a couple of minutes walk from the main square but it is also very peaceful and quiet. We definitely recommend it!