Approximately a 40-minute drive southeast of Kalamata (and 20 minutes north of Koroni, in the very southwestern tip of the Messinian peninsula) is the village of Agios Andreas, twinned with the village of Longa. Laid-back with friendly locals, it is ideal for a stopover for a day or two off the beaten path.
It has everything the independent traveller might wish for: plenty of rooms to rent, small hotels, and a camping site for tents and caravans on the beach. Local tavernas and psistaries (grill houses), pizza places, and cafeterias offer no-nonsense food at low prices. And, of course, the village has a long beach suitable for children, too.
August is to be avoided, as the local expats return back to the village in the hundreds, but the rest of the summer season is otherwise reasonably quiet. Locals who speak English will offer you the traditional Greek hospitality and be an enormous source of information for visiting places or beaches off the beaten track.
On the hill above Agios Andreas is the village of Longa, with even more traditional and untouched character. Unfortunately, there is no option for rented accommodation or restaurants there, but you can soak in the village atmosphere in the local kafenio (village coffee shop), observing the locals playing tavli (backgammon) or prefa (a Greek card game) or gossiping about politics.