I grew up attending St. Catherine's school in Norwood, MA and coincidentally now am a member of St. Catherine's parish in SC.
St. Catherine was a towering character in her time: combining great love for the Church and the Pope, but not afraid to offer fraternal correction. She had a great desire for martyrdom, but was preserved for other tasks (God's will be done!).
The only book I have read about her was "Lay Siege to Heaven" by Louis De Wohl (recommended).
St. Catherine of Siena-ora pro nobis!