Memoirs, Correspondence and Manuscripts of General Lafayette by Lafayette
Puckler-Muskau, Lady Morgan, Lady Hester Stanhope, etc.
Being secret letters from a gntleman at Paris to a nobleman in London 1799-1815
Some Thoughts Concerning the Stage in a Letter to a Lady (1704)
Don't miss Vol. II & III
Earl of Stanhope, 1746-47 (more up through the 1770s)
Early America and Travel
Don't miss all the other volumes!
The Letters of Horace Walpole, Earl of Orford Volume 1 by Horace Walpole
Letters from 1801-1820
The Letter-Bag of Lady Elizabeth Spencer-Stanhope Volume 1 - Project Gutenberg