I just saw your inquiry but couldn't have said it better than Tony did.
I agree completely that if you had to have only one line it would be a hi-density sinking head line that matches your rod. If you do have the luxury, it's nice to have a floating line rod along since the fish are very surface oriented the first hour or two and later in the evening, sometimes all day but most days it's a dawn/dusk thing. The floater keeps the fly skipping, lifts easy and is a pleasure to cast.
Hope we can hook up this fall!