What about Chai tea? One of my current favourites is Chocolate Mint Oolong tea.
I just got the chance to look these up. I've heard of them, but never tried them. Might have to at some point. It still looks like it's an "at home" drink for me vs "on the road" drink, but even if I could completely kick the soda habit at home it'd be a step in the right direction.
Thanks for the suggestion!