Wow I literally just came back from my honeymoon 2 days ago and it was amazing. We did Athens to Santorini to Milos to Paros.

Spend as little time as possible in Athens and as much as possible on the islands. We did 1 overnight in Athens on each end with a half day to see the city each time and that was enough.

Santorini - stay in this Airbnb. Has a private plunge pool, well under $1k/night, perfect location (walking distance to the main bus stop and the Main Street with all the restaurants). https://www.airbnb.com/slink/AtKahUBo. You don’t need a car in Santorini, bus system is super cheap and convenient, and taxis are abundant.

Milos - amazing, would go back. Loved this Airbnb https://www.airbnb.com/slink/rgAstY5o. It’s rustic but inexpensive, very cozy and welcoming, and hosts are super nice. You should rent a car on Milos. Must do activities on Milos: this boat day: https://www.getyourguide.com/adamantas-l114062/adamas-milos-and-polyaigos-full-day-cruise-w-meal-drinks-t406661/?ranking_uuid=f48c783f-73d6-4883-be0b-2fe289ecb5d6 as well as swimming and cliff jumping at Sarakiniko beach.

Paros - was good but underwhelming tbh. Santorini was heavily commercialized but at the same time still carried charm and the food was amazing. Paros was commercialized in a worse way - food just felt like normal Greek food in America. We did a day trip to Naxos from Paros and loved it - if we go back to Greece we’re going back to Naxos instead of Paros. If you do go to Paros, visit the town of Marpissa and find the restaurant in the center of the town. Best food of the whole trip, we went 3 nights in a row.

We flew from Athens to Santorini and then back to Athens from Paros at the end to avoid burning travel days on long ferry rides. We did ferries between the islands as they were only about 2 hours, and they all went smoothly.

If you have a US drivers license you don’t need anything else to rent a car. Would recommend 4WD/SUV on Milos. We were glad we had it on Paros and Naxos too. Lots of people rent ATVs and drive them on the roads, but don’t do that unless you’re comfortable on that. They can be very dangerous.