I like these also, I like them a lot. This one version of "Historical" that I can really sink my teeth into.
The Saint-Germain Cycle
Hôtel Transylvania (1978) is coincident with the historical Count Saint-Germain, set in the France of Louis XV, and involves his interaction with a cult of Satan-worshippers who threaten various men and women of his acquaintance. His principal romantic interest is a young lady, Madeline de Montalia, whom he changes at the end of the novel and who is a frequent companion in books with later settings.
The Palace (1978) is set in Florence in the time of Lorenzo de Medici and Botticelli, who appear as characters.
Blood Games (1980) is set in Nero's Rome. His romantic interest in Olivia Clemens, a battered wife whom he changes and who survives (and is featured in her own series of novels) until a fire in the 16th century.
Path of the Eclipse (1981) involves St. Germain's escape from Genghis Khan through Tibet and India.
Tempting Fate (1982) is set in Europe after World War I and chronicles the rise of the Nazi party in Germany.
The Saint-Germain Chronicles (a short story collection) (1983) In five stories set in the 19th and 20th century, St. Germain explores various parts of his life. The final story, "Cabin 33", is the latest story in the canon, set at a dude ranch in the American West owned by St. Germain and Roger, and concludes with St. Germain and de Montalia deciding to see if they can break with vampire tradition and live together as husband and wife.
Out of the House of Life (1990) principally concerns the adventures of de Montalia on an 1810 archaeological expedition to Egypt, punctuated with long letters from St. Germain which contain information she uses to find artifacts left behind from his "life" there. However, St. Germain only appears as a character directly for a short period at the end of the novel.
Darker Jewels (1993) is set in the Russia of Ivan the Terrible.
Better In The Dark (1993) is set in Germany in the 10th century.
Mansions of Darkness (1996) features St. Germain in Spanish America in the 17th century.
Writ in Blood (1997) features St. Germain as a secret agent of Russian Tsar Nicholas II, attempting to patch the ties of blood between the European royal families and prevent the outbreak of World War I.
Blood Roses (1998) is set at various locations in France during the Plague years.
Communion Blood (1999) is set in Rome in the late 17th century.
Come Twilight (2000) is set in Moorish Spain.
A Feast in Exile (2001) is set in India at the time of Tamurlane's invasion.
Night Blooming (2002) is set in the Frankish kingdom of Charlemagne.
Midnight Harvest (2003) features St. Germain's visit to the United States following the events of Tempting Fate.
Dark of the Sun (2004) is set in China in the 6th century.
States of Grace (2005) is set in Western Europe in the 1530s.
Roman Dusk (2006) is set during 2nd century BCE Rome of Heliogabalus
Borne in Blood (2007) is set in Switzerland in the 1810s
Saint-Germain: Memoirs (2007, short story collection) features St. Germain in various time periods
A Dangerous Climate (2008) is set in 18th century St Petersburg, Russia
Burning Shadows (2009) is set in 5th century Hungary and Romania
An Embarrassment of Riches (2011) is set in 13th century Bohemia
The Atta Olivia Clemens novels
A Flame in Byzantium (1987) is set in 6th century Constantinople during the reign of Justinian I
Crusader's Torch (1988) is set in 1189 AD during the Christian Crusades in the Middle East
A Candle for D'Artagnan (1989) is set in France during the 17th century reigns of Louis XIII and Louis XIV
The Madelaine de Montalia novels
Out of the House of Life (1990) is set in an archeological expedition to Egypt during the 1820s.
In the Face of Death (2004) is set in the United States just before and during the Civil War.http://www.isfdb.org/cgi-bin/ea.cgi?Chelsea_Quinn_Yarbro