In order to give yourself an overview and familiarise yourself with navigating around the map, you should first of all resize your chosen map area. Typically a section of airspace covering a very broad region around your location is usually displayed first. Clicking on the ‘Magnify’ button, represented by a plus (+) icon, will make the section smaller. This reduces the number of aircraft displayed and immediately gives you a clearer view. When using Flightradar24 on a mobile device, you can zoom in the usual way using the touch screen.
Comfortable accommodation in May for 2 persons can be found for between €40 and €80 per night. A meal for two that includes a starter, two main meals, salad and a litre carafe of local wine will cost you around €25-35. This can vary widely depending of level of establishment you eat at. A cheap vegetarian dish (pulses or vegetable) will set you back by no more than €5-6 a plate. If you get your breakfast included at the hotel, that is good because breakfast can add another €15 for the two of you per day.
Be cautious with Santorini and kids. Some hotels don’t do kids (check carefully) and not all hotels are suitable for kids along the caldera lip. Many steps, confined spaces and other guests who don’t actually want to hear kids … Here’s an idea – look for a child-friendly hotel (perhaps on the beach at Perissá) and base yourself where the kids will like it and then take them to the caldera scene. There are a couple of child-friendly hotels on the Caldera, but they get booked very early in the year.
Yes, I would agree that 8 or 9 days is too long for Naxos – unless you’re happy sitting at the beach for several of those days. But if you’re looking to be semi-active and explore then you’d be best to add Paros and spend 4/5 days on each. Crete, on the other hand, would be perfect for an 8/9 day road trip. Start in Heraklion (where the ferry arrives from Santorini) head east and then south and finally ending up in the western town of Chania where you can fly up home from.
Can you see all the major sights in Athens in one day? No. But you can see the Acropolis, Acropolis Museum, and the top historical sites of the Plaka in one day. If you had an extra half-day then visit the Archaeological Museum in Exarcheia. That still leaves many great sights but you will have seen all of the iconic Athens attractions. Adding Naxos is always a good idea. You might even enjoy it more than Mykonos (but no nightlife like Mykonos).