During the course of a single day I managed to visit all eight of the listed churches, thanks to the advice and help I received. As it was a Sunday all the churches were open, and many of them well populated. Only at Patrauti was I alone, but even there the priest came and opened the church for me.
All the churches were worthy of a visit, but I thought Voronet and Moldovita the most colourful.
For anyone else visiting these churches I would recommend seeking out Lucy at Hilde's Residence, a renowned guest house in Gura Humorului.