Culebra Island is beautiful. I just got back to Canada from Puerto Rico. I was there for a month. I loved Culebra so much I went back twice. On my second trip I spent two nights camping at Playa Flamenco. I paid $20 USD per night for a sweet little camping spot (section E). I saw turtles, amazing, colourful fish and met some wonderful people. The snorkelling was okay in terms of being able to see under water but the reefs are not healthy. There was plenty of coconut to pick to drink the water inside and eat the meat. I found passion fruit, mangoes (not ripe), almonds (not ripe) and another really weird looking fruit I don’t know the name of. While I didn’t enjoy the main island of Puerto Rico as much as I’d hoped, I would go back to Culebra if the opportunity ever arose. I made some friends (Perri and Hector–owners) at a little place in town called, “Aqui Me Quedo” who I will never forget their kindness and hospitality.
It’s a tough call. The good news is that whatever you decide, it will feel like the right thing after you’ve done it. You’ll almost certainly say to yourself, “I’m so glad we saw both islands” or “I’m so glad we had 6 full days on Santorini.” In deciding I would ask whether a return trip to Greece is likely or possible in the next couple of years. If so, then spend your 6 days on Santorini and explore that island, then return to Crete at some time in the future for a deserving 7 to 10 days. But if this is a one-time deal for the foreseeable future then do 3 days on Santorini and 3 days in Crete. (Whatever you decide don’t do a day trip to the other island as it’s not worth the time and effort.)
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.
Easily reached from both Split and Dubrovnik, Lastovo is packed with 15th- and 16th-century architecture, including countless churches in different styles. The island is rich in history, and the main town is full of the various types of architecture, including beautiful Renaissance houses. Lastovo and its surrounding islands is Croatia’s newest Nature Park.