For drinks, such as sweetening tea or koolaid, I use white sugar. Now, if I'm making apple cider, then I will use brown sugar because white sugar just doesn't give it that taste I'm looking for.
When I am making up my own recipe, like my glaze for a ham, then I tend to use brown sugar more often than white sugar. In cookies and cakes, a lot of the recipes call for both white and brown sugar.
I hardly use brown sugar at all, only if a recipe requires it, and it clearly can't be substituted. I don't really tend to use that much white sugar either, this isn't because I'm a fitness fanatic-- far from it, but because I don't drink that many hot drinks, as I don't drink tea or coffee, I don't need any sweeteners!