What book is recommended to learn more about the saints?
For the lives of saints? See a Synaxarion such as The Synaxarion: March, April Volume 4: The Lives of the Saints of the Orthodox Church by Hieromonk Makarios (1998) (and the other volumes for other months, of course).
Thanks, we really should have that in logos
We have one title by Sebastian Dabovich that covers the lives for fourteen Saints important to the Orthodox faith. A lot of the material in Butler's work is relevant, as well. Then there's The Fathers of the Desert (2 vols.) and Select Narratives of Holy Women.
Beyond that, you should know we're working on a Saints database for our Orthodox users that is comprehensive for every day of the year (similar to what Verbum has for Roman Catholics) to go alongside a Byzantine or Orthodox lectionary (both Julian and Revised Julian calendars).