I visited this WHS in June 2014. I spent 2 days here and I got to visit both main Sassi areas (Sasso Caveoso has more to offer) as well as a number of Rupestrian Churches and cave homes. The best views of the Sassi and Matera in general are the Belvedere just opposite (some 6km away by car) and the view from the Convicinio di Sant'Antonio. The combined ticket that gives you access to all the Rupestrian Churches costs 7 euros and all are definitely worth a visit. However, my personal highlight was the Santa Lucia alle Malve with its beautiful frescoes and engravings. Flash photography is strictly not allowed and when there are several groups no photos are allowed to avoid waiting times. The caves opposite Matera (near the Belvedere) are worth a hike mostly for birdwatching (mostly swifts and lesser kestrels) and to enjoy the flora and different butterfly species. However, some of them are painted with frescoes and the best one is Madonna delle Tre Porte (marked 102 in the orange hiking trail). There are a couple of cave homes that you can visit to try to imagine what it must have been like to live in such conditions.