Flavor concentrates are indeed a great way to enhance the taste and color of non-alcoholic drinks. They are highly concentrated, so a little goes a long way. You can find a wide variety of flavors, from classic fruit flavors like strawberry and blueberry to more unique options like lavender and rose.
Try adding herbs like mint leaves or basil leaves can be a great way to add. Simply muddle the herbs in the bottom of your glass, add your desired liquid, and enjoy!