One Week in Peloponnese -- What to do?

Have you thought through the day-to-day? When you plot this out more specifically, it helps 'see' the amount of time you'll want for each place (site seeing plus down-time). Personally, I think you might have too much time in Monemvasia. I think an evening and morning there is sufficient, unless you plan to use it as a base for surrounding trips like Ermioni. Kardamyli can be a good base for the Mani if you want to see some of that, or just to explore the coast where Kardamyli sits.
Depending when you arrive in Nafplio, you could have 'too much time' there. Part day on arrival day, day 2 + 3, then part day 8 + 9, but I also think your pace looks good, so 'too much' is really relative
You could spend one night in the Arkadia region en route to kardamyli (and thereby push your whole itinerary forward by one night, and lose the second night in Monemvasia) in Stemitsana or Andritsaina. Near Andritsaina is the Temple of Apollo Epikoureios at Vassai.
I think you are wise to take your time, stay a few days in each, and leave room for exploring. I wouldn't change your plan by much...

Jessie

When we went to Mystra we stayed overnight in the Byzantion Hotel in the village at the bottom of the site. It’s nothing special but comfortable enough. It also has a small pool which you might appreciate in July. In the evening the village becomes pretty quiet, and is quite atmospheric, and there are two or three nice places to eat.

If I were you I’d be tempted to stay there rather than do the trip back to Nafplio for one night.

Alan

It's been 10 years since I was at Nafplio but -> it was so nice that we wanted to stay there longer
i.e. sleep there and day trip more
We went to Mycenae and Epidavros and where glad to have done both.
Corinth was important to see, as a Christian, but was not as good to visit as either of Mycenae or Epidavros

Great suggestions! Thank you!

The first reply mentioned using Monemvasia as a base for Ermioni. How is that possible? I don't see any ferries that run but the ferry pages are very confusing.

Jessielaurel, I think that was me. I got my places crossed - I meant Elafonisos (the island) and not Ermioni (a town). Here is instructions for getting to Elafonisos (drive + ferry), and you can drive to Ermioni:

https://www.greecetravel.com/peloponessos/elafonisos/index.htm

And here's google maps (it takes ~90 minutes to get there from Monemvasia):
https://www.google.com/maps/dir/Monemvasia,+Greece/Elafonisos,+230+53,+Greece/@36.6372817,22.6743712,11z/data=!3m1!4b1!4m14!4m13!1m5!1m1!1s0x149e41d1e40eaa5f:0xdb7d0a06b9f3bb31!2m2!1d23.056032!2d36.6876016!1m5!1m1!1s0x149e0cf9f4f4a237:0x2cbe2723ac08c197!2m2!1d22.9594983!2d36.4875509!3e0

Thanks, Jessica! Elafonissos looks gorgeous and like a place my husband would love, so I think we'll try to work that in.

Another place that might be worth a look is Xirokambi.

http://www.xirokambi.com/wordpress/

I’ve had it on my list for a while but haven’t made it so I’m not sure if it’s a really nice place or just somewhere which has a good web designer living there :-)

If you give it a go be sure to come back and let us know!

Alan

Thanks, Alan! Xirokambi does look nice and it should be easy to spend time there on the way to Sparti/Mystras. But I see what you mean about the possibility that someone with website skills lives there! I will report back if we make it.

dear jessielaurel,
hi! i am in greece and we are almost finished with our trip. we followed rick's book exactly. we are in kardamyli and tomorrow we head for monemvasia. i am devastated. my daughter didn't notice the book fell out of our car at the parking lot where the underworld archaeological site at the most south point of the mani peninsula and i am devastated because i rely on the book heavily. his books are the bible of travel to me. anyway, can you help me!? i know about the rock, upper and lower towns of monemvsia, the fortress. i see you mentioned ermioni. are there other suggestions in monemvasia? or nearby?
then we go to napflio, where i will see napflio and mycenae and epidavros. i am truly sad we don't have the town walk of napfliio. i always do his walks. please can you send me what you can from the rest of the book, edition 2017 at least. i intend to buy another book when i get back, to hopefully put the notes i wrote in the book from memory.
if you at least send me info on monemasia, i can look at rick's site to glean for napflio and again write to you in two days when i leave monemvasia.
thanks truly if you can help me. desperate, gloria ho

Hi Gloria,
Sorry to hear about your predicament. Unfortunately I don't have the book yet. I've just been relying on web sources to plan because our trip isn't for another month. Good luck!

Been there. Go to amazon and download digital copy to your pad/phone. I like the hard copy but digital will do. Left my book in a taxi in Belgium a couple years ago, downloaded digital as soon as we got to hotel