My husband and I just returned from 3 weeks in Greece, mostly exploring the Pelopennese, and I just wanted to offer some feedback and tips for anyone considering such a trip. I used this forum, the RS Athens guide, Matt Barrett's website and Facebook group, and the Bradt and Cadogan Peloponnese guides for planning.
Airline:
We flew Turkish Airlines from Seattle to Istanbul to Athens. This was my first time flying TA and I was very impressed. The seat size and legroom are commensurate with Delta Comfort+ (my usual choice), seat pitch is better, and the food quality was much better and very plentiful. They even gave us lunch on the ~2 hour flight from Istanbul to Athens! Service was also excellent and I loved the little amenity bags. Our flight out was delayed about 2 hours but we made up time in the air. Ground agents met everyone at the gate in Istanbul, sorted us into groups by connection destination, and escorted each group through back routes to their planes so we all made our connections.
Athens - 4 nights
We used Welcome Pickups for the airport transfer which cost €50. I read a lot of comments from other travelers about getting scammed by taxi drivers so having a price agreed to was important to me. The service worked very well.
I don't like overly touristy areas and I chose to stay in the Psyrri neighborhood for its artsy more hip vibe. I chose Athens Center Square Hotel based on the RS recommendation and for its proximity to the market because we are also foodies. Arriving at night I wasn't sure about my choice -- the streets are covered with graffiti and it looks quite rundown. Even our driver questioned my choice. But during the day it's very vibrant and a real working area, we loved it. There are lots of great bars and restaurants within walking distance and it just had a more "real" feeling than Plaka did for me, plus no tourist hordes.
The hotel service was excellent, especially the front desk, and having breakfast included was a real plus. We had a room with a view of the Acropolis and total was less than $750 for 4 nights so I thought it was a great value. Only gripe is that the bed was 2 twins pushed together but still separated. My hubby ate something bad at a restaurant we visited and had a couple down days here so maybe it's just as well we were separated.
Favorite meal was at Avli - excellent service and food, and the prices were fantastic. Krinos loukoumades nearby shouldn't be missed. We also really enjoyed drinks at Couleur Locale with an amazing view of the Acropolis at the sunset golden hour right after our walking tour there. We used Athens Walks Tour Company for the Acropolis tour and it was good, I liked that the group wasn't too big.
Reports for the remainder of this trip:
https://community.ricksteves.com/travel-forum/trip-reports/trip-report-greece-part-1-athens
https://community.ricksteves.com/travel-forum/trip-reports/trip-report-greece-part-2-kardamyli
https://community.ricksteves.com/travel-forum/trip-reports/trip-report-greece-part-5-nafplio