Iced teas are generally watered down when finally given to you. If you ask for no water, the barista will add only in the required amount, and your drink will have a much stronger flavour.
The iced teas are also artificially sweetened and the taste of the drink suffers. If you prefer a more natural taste, you should opt for Starbucks' more organic teas.
If you like more flavour than water, try this: Order hot tea and chai teabags, and ask them to top it off with hot milk. It works out to be cheaper, and you get more flavour.
Instead of asking for a Caramel Macchiato, you're better off going with a Marble Mocha Macchiato, which will add a little more flavour, and contains a better balance of white mocha and caramel.
If you want your drink to be a little less hot, you can order it at a “kid’s temperature”. The drink will be served at a reasonable temperature, allowing you to drink it without scalding your mouth.
Instead of ordering an iced latte, order a Doppio and then pour in whichever milk you prefer yourself.
The chai lattes are actually made with added water so that the flavour is even, you can instead ask them for the drink without water, and you'll be able to taste the cinnamon/chai flavours better.
The half-and-half refreshers will really help you beat the heat. Cool Lime and Berry mix together very well.
An Americano tastes much better than most of the drinks, because it's espresso-based; all you have to do is add a little milk.
If you're going to be sitting at Starbucks for a long time, it makes more sense to order a French press of coffee instead of multiple drinks.
When ordering a Frappuccino with an extra shot, ask for the "affogato style," and they'll pour the shot on top of the drink. This creates a better shot-to-drink ratio.