Why only two flavors a day? Personally, I hate water. Always have. I've gotten better about it, and I make myself drink it anyway, but there are times when it really makes me gag. I flavor mine with SF syrups whenever I can to make it palatable and keep things interesting. Water has a positive, cleansing effect on the system, but I don't see how that is lost by the addition of flavor.
Perhaps my weight loss might progress more quickly if I drank only unflavored water, I don't know. What I do know is that I've lost 49 lbs. since 10/4 and I'm perfectly satisfied. I love the variety that flavors have added to my diet and I enjoy mixing up Italian sodas just as much as I did when I was shaking up weekend martinis.
I saw something on the Today show recently where they were talking about how much water should be consumed in a day and don't quote me, but the gist of the advice given was that with other (non-caloric) beverages do count toward that daily intake. This, of course, doesn't mean we should be downing caffeine-laden soda all day, I'm sure; but within reason, I don't see how beverages that are 99%-plus water cease to be beneficial as a result of flavor. If they are slightly less beneficial, I would expect that drinking them is still better than not drinking them.