At the Starbucks on Fort Campbell Boulevard in Clarksville, Tenn. -- two miles from the U.S. military base -- store manager Shannon Feltz pours hot coffee for a group of veterans seated at a communal table. On a shelf next to the register are rows of green-and-white mugs reading: "Proudly serving those who serve." On Tuesday, the Clarksville store became one of 37 around the country designated by the coffeehouse chain as "Military Family Stores" -- stores staffed primarily by veterans and military spouses as part of a larger effort to employ service members and their families nationwide. "Seventy-five percent...