As an armchair history buff, I love famous historical people who were also prolific letter-writers. It gives a great insight into the person, especially when the letter was between family members or close friends and never intended for public consumption. (Reagan was one of these people) As much as I like Letters of Note for the great letters, for me having a stream of letters makes the person much more three-dimensional.

The book on the Adams-Jefferson letters has been on my reading list for a year now. Can't wait to get time to read it. http://amzn.to/MudjlA I believe there is a similar book for Reagan, but I haven't researched it. Enough stuff on the list already.