Usually Club Soda or Sparkling Water. I hate sweet drinks like Coke/Pepsi, and hate the sugar free crap even more. If early AM, black coffee. BUT, when I am coffee-ed out and it's too early for alcohol, I too drink tomato juice or bloody mary mix, and I NEVER drink these unless I'm flying. Why is that?
Otherwise, it's always Scotch and soda or on the rocks.