What is your favorite part of history to read/learn about?

Six Frigates is excellent! if you liked Six Frigates, you may also like Broadsides: The age of Fighting Sail by Nathan Miller.

Also, there are some old illustrated Time-Life books that are really cool (if not historically weighty or significant) -- I have the Fighting Sail and Men of War titles -- nice blue cover -- great for coffee table browsing.

You can get them really cheap on Amazon (although mine are original so I don't have any idea of the used quality there).