Club soda with frozen fruit, fresh mint, and oj. Pellegrino with grapefruit. There are some blood orange or fizzy lemonade things that you can buy too. Actually I just hit up the grocery store for some fancy drinks that don't have alcohol and I was surprised at how many there are.
Also I find that if you mix anything sugary like pop or lemonade or with a bunch of club soda, its a lot less sugar and tastes almost the same or better.