I just drink water and milk. I miss juice and pop, but heartburn is not worth it! I work for Starbucks and believe me it was hard to give up the bean juice! I know it is ok to have a cup or two a day, but I decided to just plain stop. I usually start the day with a cup of tea, less caffeine.
As for carbonated as pp said, try seltzer or club soda and add lemon or lime? I would have a ginger ale once in a while too, especially during 1st trimester.