As a child I was real interested in the Civil War, American Indians, and the American West. Then WWII, as almost everyone in my father's and grandfather's generation served somewhere. My father ended up as a career soldier, which allowed me to talk to a lot of WWII, Korean, and Vietnam conflict veterans as well. My grandfather survived both Dieppe and the 'Frozen Chosin'.
College era focus was on Inner Asian history, specifically the waves of nomad invasions off the steppes into Europe and the middle east. Huns, Turks, Mongols, etc.
Other directions as I find the time. Oh, and Chinese history. Became real interested in and did some extensive reading on the Boxer Rebellion in China.