You might want to have a look at: AVA Hotel, Apartments & Suites. It's #1 on tripadvisor.com (Grand Bretagne is #2). They appear to have rooms that accommodate more than 2 people, and is highly rated, and in the Plaka. It's also very small, so might be hard to find a vacancy.
Wendy ------ Booked: Uniworld Egypt, 2015 Tauck Amsterdam to Budapest, 2016 Paul Gauguin, Societies & Tuamotus 2016
🚢 Cruise with your favorite Keene Luxury Travel Staff Member! 💰 5% KLT Reward plus Shipboard Credit available (amount varies per voyage)! 💲 Offering Enhanced KLT Rewards on voyages hosted by Ngaire & Clay!