Help With December Driving Itinerary Northern Greece and Peloponnese

I don’t think you have too many nights for Nafplio. We spent four nights there, although it was June and we spent time at the beach.

Eight nights does seem a lot for Athens to me.

I agree with BethFL that you could remove a few nights in Athens if you find other places to spend them or reallocate them to places you're going.

Don't change the last four nights in Athens; you'll be there to catch your return flight.

Some Timing Considerations

In winter, the Delphi site closes at 3:30 PM and the Monastery of Hosios Loukas at 4:30 PM, and you'll have about a 3-hour drive to get to Delphi without any stops.

Including the stop at the monastery (about 1 hour) and possible lunch stops and breaks, you'll need to leave Athens no later than 9:00 AM to be in Delphi on time before the site closes. When I say 9:00 AM, I mean 9:00 AM in the car ready to go, not leaving the hotel at 9:00 AM. So also allow time for car pickup.

Unless you plan to visit Delphi the next morning, in which case it will delay your departure to Kastraki via Thermopylae, and the same problem will arise for the Meteora monasteries, which in winter close quite early in the afternoon (2 or 3 p.m.).

I assume you'll then go to Monodendri via a stop in Metsovo for hiking activities (Vikos Gorge), in which case keep the 3 nights you planned.

Regarding the Dimitsana to Stemnitsa hike, I hope you've already inquired about taxi options; otherwise, see the taxis available in Dimitsana:

https://menalontrail.eu/en/taxi-transfers/.

You can also consider taking a taxi to Stemnitsa and hiking back to Dimitsana.

The hike description is here:

https://menalontrail.eu/en/activities/section-1-stemnitsa-dimitsana/

Needless to say, for all these hikes, take the weather into account. It will be winter in a mountainous environment.

I don't think that's too many nights in Nafplio either--there is so much to see in the vicinity, and I would imagine the town would be very nice in winter.
I would not feel the "need" for that many nights in Athens, but it's always easy to fill time in a city. OTOH I think you probably should put a night or two toward your other stops, especially given you might want flexibility when it comes to weather and long drives--and serendipity.

You could cut a day from Athens.

Also, consider visiting Corinth and the Corinth Canal.
Consider doing the one day three island tour from Piraeus.
The Temple of Sounion a few miles east of Athens.
Don't miss in Athens the Museum of Archaeology and the New Acropolis Museum.
You didn't plan to visit any of the Greek Islands. If you had more time, you could visit Mykonos, Santorini or Rhodes.

This is all super helpful, thank you! I will leave Nafplio as is and keep the last 4 nights in Athens. Is anyone familiar enough with Dimitsana in December to know if there will be enough to see and do there to warrant adding another day in that area? Will restaurants be open or are things shut down in December? I did note the taxi issue and will plan to start our hike from Stemnitsa not Dimitsana as JoLui recommended.

I was told that the Dimitsana area is a popular getaway for Athenians (and skiing nearby) so I would expect it to be fine in December. We did the monastery gorge hike and had some nice dinners, but I really wish I had devoted more time to the towns.

I didn't make it to Dimitsana but did go to one nearby village called Karitena early October.

The entire area is mountainous and is slow going by car but beautiful scenery.

I did find this on a website regarding weather in Dimitsana:

"In December the climate is very unfavorable. At lunchtime, it's 52°F in average and it rains about 5 in the month."

That's an average so it could be warmer or colder and possibly snow depending how late in December you are going.

Something to consider.

I read on a blog about someone who did this hike in early December and has lively weather. But certainly no guarantee.

I am planning to visit Dimitsana next May and one thing I have read in several different places to consider is that the hike from Dimitsana to Stetmnitsa is less strenuous than the other way.