Most importantly, if you are going to be sitting in the store, order your drink in a ceramic cup--if only to get a better deal. I've found that about half the time, ordering a tall "for here" gets me a Grande mug (see photo). Also, quite often, the "cents off cup" discount of 10 cents is applied, even though this is technically for customers who bring their own cup.
If you go to a Starbucks, go to one that isn't in a neighborhood with the stereotypical Starbucks
demographic (college-educated, $100K+ household income, childless, yada yada yada).* A Starbucks in such an area needs only to hang out its shingle to make its numbers. Classic example: the N. Downer Ave. store, the one at which I have the hardest time having a satisfying experience.
There's a big exception to every rule, and the Mequon Starbucks on N. Port Washington Rd. is one. I think it's my favorite Starbucks.
Go to a Starbucks for which the sales figures are watched closely by district managers on down. I have no way of knowing, but I'd guess the 27th and Oklahoma store fits this profile.
In my experience, the 24-hour Starbucks on Hwy. 100 is the most notable exception to this rule.
*Though they sometimes have cute female employees (like the one in the East Pointe strip mall on E. Ogden Ave.)