I've had those drinks. Really, it's best to go natural. You know the old saying, "If ya hafta ask..."
To help get off of my soda (and aspartame) crutch, I've been mixing a tablespoon of CM in a tall glass of water. Gives the water a sweetness, makes it go down real easy, and I get extra fat. With ice it is extra-super refreshing.
I do keep an eye on total calories, which is why I use only a tablespoon in a big glass - it is only about 20 calories. I'm just not going to drink enough of these in a day to add much to my caloric intake.
Aspartame makes me crave carbs (I figured this out even when eating SAD). That I still regress and am lured by diet sodas just reveals its highly addictive nature. At least for me.