I don't go very often, but when I do I usually get a triple-grande non-fat latte with a splenda and nutmeg (the nutmeg makes it soooo much better).
I used to get the flavored syrups, but the sugar free syrups start to taste nasty after awhile and I don't want the empty calories of the real stuff.
I have also been known to order a chai tea with skim milk if I don't want the caffeine of the latte.
And even though Starbucks is very expensive, I can tell a huge difference in taste between it and what you find in most offices. I don't drink coffee that often, but when I do, it's usually Starbucks.