Overnight on the Mani

Is this a just one night stay in the Mani and traveling onward from there?

It's a large area and would need several days to fully experience.

Are you interested in beaches, mountains, small villages, lots of options for shops, markets and tavernas?

More info would be required to give you a good response.

However, some of the better towns would be Kardamili, Areopolis, & Gythio which are large enough to offer enough services.

Many other smaller towns to consider but more info is needed for a good recommendation.

crazyh has provided probably the best suggestions with each of these towns decent size.

On our Mani trips we have stayed at Gythio, Aeropoli and Kardamili. The prettiest village was Kardamilli but it is pretty remote for the rest of the Mani as it is tucked behind mountain ranges on both sides.
We used it as a base to visit Ancient Messena near Kalamata. I found it to be a bit too far away to use as a jumping off spot for the southern Mani.

Aerolopi is very nicely centered. You can even stay in a converted tower house in Aeropoli. For day trips you can do Diros Caves perhaps Kardamili. From Aeropoli you can do a pretty good long day trip around the Mani and end up in Gythiio for the night. Gythio is also close to Monemvassia and Mystras two more spectacular sites although technically not in the Mani.

Here is our trip last September
Mani https://www.flickr.com/photos/stanbr54/albums/72157711323535897

I agree that Mani needs more than one night. Check out the almost deserted town of Vathia. I second the suggestion that Kardamilli is a lovely place to stay.

Stanbr, thanks for sharing. Wow! that took me back to one of my all time favorite trips!! My kids thought there should be a calendar called "cats of Monemvasia," and as we walked around they would discuss "that's January cat," "oh that one is in shape and should be July cat," etc... So fun to see all your cat pics too!

Our plans include nearly a week at a resort in the Costa Navarino area followed by a drive back to the Athens airport. We figured we'd drive through the Mani and stay 1 night before getting closer to the airport for our last night.