We had two relaxing, perfect weeks here in the second half of June (plus a weekend visit from two more adults who were seduced by the pictures!). Beynac is a lovely village, much more beautiful (in our biased opinion) than the more famous La Roque Gageac just upstream, and you really can spend days here without going anywhere.
There are canoes for hire in the village – they drive you upstream, and you paddle back down to the village, the castle of Beynac is lovey, and Castelnaud is a riverside walk away, with a museum of medieval warfare which our boys (aged 9 and 8) loved. It is a drive to get to the prehistoric caves (Font de Gaume, around 20km away, is the last multicoloured prehistoric cave that is still open to the public – book before you arrive if you coming in summer), or to a big supermarket, but you can buy everything you need in the village in summer. You can even go for a hot air balloon ride if that takes your fancy.
The pool was a godsend when it got hot (37 degrees on our hottest day) and there are marked walks in the countryside on cooler days.
The only downside for us (as has been mentioned elsewhere) was the internet – it is fairly weak (as it is shared with a neighbour) so the signal is only strong enough for PCs from one room in the house and the terrace. It is impossible to access from an iPad or iPhone or Android (we tried several) and the weak signal connection makes it difficult to do much more than pick up emails.
Other than that, we loved the place, and only wished we had booked three weeks instead of two.