Starbucks is known for its customizability. You can choose anything from sizes, to flavors, to milks, down to even the temperature of some beverages. At Starbucks, you can get exactly the drink you want, so it is no surprise that their caffeine-free beverages would be the same.
At Starbucks, if you want, you can get something as simple as Steamed Milk. This simple beverage is typically marketed on their kids menu, but is available for anybody to order.
If you want to jazz it up, Starbucks offers a plethora of syrups and sauces that can be added to the mix to give it a bump of flavor, without the bump of caffeine. While the mocha sauce does contain some caffeine, other flavors do not. Flavors such as hazelnut and caramel are available, as well as fruity flavors such as strawberry and raspberry. Sugar-free vanilla is also available for those looking to avoid added sugar. Starbucks will let you do any combination you want to achieve your perfect desired drink, all without adding any caffeine.