If you go to Sarlat, make sure you drop in at the shop of Francis Annet, Rue Valéry. I assume he's still around - he does books and prints, and my wife and I bought a book or two as well as a few of the prints which I still have on the bedroom wall; one is a misty close-up of some grapes in a sunset/sunrise light and the other a very atmospheric high view across rolling hills with lots of mist in the valleys. A Nikon/Velvia man with the perfect venue for selling his own work.
La Roque-Gageac can give you more rain than you expect and it sometimes floods to street level. The Dordogne may look friendly, but no big piece of water ever really is - treat with respect!
We used to stay a few nights at the Hostellerie de la Paix in Payrac (they have a web address, and were in the Logis de France system at the time). Modest, inexpensive rooms but excellent cuisine at fair prices. That's not far from Rocamadour, and I remember missing some great ballon shots there: I had run out of film at the psychological moment as several of the globes rose from the valley floor far below and drifted upwards, outlined so horribly well against the sky beside the turrets of the castle I had been shooting.
Another nice location for a hotel is right on the banks of the river itself, the Du Chateau at Lalinde. A couple of rooms are overlooking the water; though we never stayed there, always meant to, despite the midges. But if you have been to Scotland or Canada, what the hell!
Rob C