If it's good enough for Mark Twain, it's good enough for us. Follow in the great wordsmith's wake on a paddlewheel cruise down the mighty Mississip', and stop in for ribs in Memphis, a blues concert in the Delta or some jazz in New Orleans. You can also find river cruises on northern rivers like the Ohio, and if carpe diem is what floats your boat, head west to the Columbia and Snake Rivers for some serious scenery.