The Peloponnese for 4 nights

Keep the three nights in Napflio. We spent a night in Sparta for Mystras, a night in Olympia and a night in Delphi. We usually do not stay for just one night but it worked well in this area. I would not want to stay in the port city of Kalamata, at least the areas we drove through.

It is really tough! I spent 8 days in the region and could have doubled that and still left wanting for more.
It's about 2 hours from Nafplio to Mystras, so after lunch you will likely spend the remainder of the afternoon there. I'd pick somewhere that gives you the amount of driving you want en route to Athens. I think I would want one full day in Dmitsana, though it worked well for our last stop and was an easy drive back to ATH (comng form the south, it took us forever to get there though--perhaps we chose a bad route).
I believe ArcoCorinth requires a lengthy walk so take that into consideration with shorter days. Nemea was a relatively quick stop.

Thanks Suki and Valadelphia. I wish I had more days but I'm sure we'll be back. In looking at a lot of the responses on the forum regarding the Peloponnese I wonder if it makes sense to just skip Mystras and stay 4 nights in Nafplio, visiting Argos, and maybe the southern portion of that peninsula during a day trip. Having never been there, is that too much time in this one area, is Mystras worth the trip? Suki, did you enjoy staying in Sparta?

Also, I found winter opening times for the sites in Greece - any idea when "winter" starts? Many sites close at 3PM in winter so that would affect my decision as well.

Thanks again for your help.

Mystras is pretty great, but if you think you will be back, then I would explore the Nafplio area pretty exhaustively, and save the south and west for later. I think the Dmitsana area would be lovely in October--it is more of a cool weather destination according to our hotel, but we loved it in May. Nafplio is fantastic in all weather, so it is perfect, but in late October I'd hold off on the smaller seaside places. I think it's a tossup between all Nafplio (maybe down to Monemvasia?) or Nafplio and Dmitsana.

I would stick with at least the 3 nights in Nafplio because of the season...you do NOT want to drive in the dark, and check the October sunsets -- latter half its about 6:30... earlier if hills intervene. If you do go to Mystra, get an EARLY start... you want to get back to a big road before twilight.

I really liked Mystras (decades ago). Sparta was a comparatively unattractive modern city.

Ditto acraven: Mystras, more recently, was one of our favorite places, and Sparta was... a good place for lunch & the impressive statue of Leonidas.

Thank you all for your replies. So it seems Mystras is worth the effort. Now rethinking the trip as follows;
Instead of driving directly from the airport to Nafplio, drive to Mystras, stay near Mystras for the night - our flight lands around 11:30AM so we should be on the road easily by 12:30, arriving in Mystras area even if at leisurely pace by 4/4:30. Plenty of time to chill and go to bed early - jet lag and all. If possible perhaps we could stop at Nemea on the way. Is it highway driving all the way to Sparta/Mystras?

Then after spending our first full day in Mystras, drive to Nafplio and spend the remaining 3 nights with an easy trip back to Athens after that.

Any recommendations on places to stay near Mystras?

Tnanks again everyone!

My comfort level for driving after a flight caps off at two hours, but it is easy driving--virtually all highway. When we got to Mystras (between there and Sparta I think), we drove through some farm land--a horses in the road kind of area, but that could have been user error, lol.
The little modern town of Mystras was pleasant enough, with some cute hotels (we only passed through for lunch en route to the site). I'd just stay there unless you have interest in Sparta.

Thanks valadelphia. Am looking at staying in Mystras for the one night. Thank you all for your advice.

Re Mystra -- this fab map http://euro-map.com/karty-grecii/peloponnes/podrobnaya-turisticheskaya-karta-peloponnesa.jpg (click & it gets huuuge), shows exact route, all the way from airport ... very modern multi-lane highway thru Tripoli, then south on good 2ndary road with No traffic... you'll be fine, yours is a good plan; Do check internet for October closing hours.

Another confirmation for Nafplio. We spent 6 nights in the Peloponnese with half the days in Nafplio. So much to do in the area.

Olympia was very enjoyable. We spent 2 days down in Kardomyli. It is a tiny seaside town with some mountain trails nearby. Not a lot to do in the town but could be a gateway to nearby exploring.

We’ve stayed a couple of times in the Byzantion Hotel in the village of Mystras itself. The hotel is nothing spectacular but it’s pleasant, quiet and the people are friendly. The village is remarkably undeveloped for somewhere near such a big site.

Our favourite place to eat in Mystras was the Taverna Eleni just around the corner from the hotel. Actually, everything in Mystras is just around the corner from the hotel!

Only a couple of minutes away by car it’s worth stopping at the Fountains of Parorion. Not spectacular but if you’re passing anyway...

https://goo.gl/maps/gm3i65w6T9c96HpUA

There are a couple of traditional looking tavernas here. I imagine people come out from Sparta to eat here but we’ve never tried them.

Alan