There are actually a whole bunch of good medium to dark roasts out there, but third wave coffee is hip and has been for a while.
If you like Starbucks beans, you'd probably like a better dark roast. Try Lavazza. Coffee snobs will look down on it, but they're highly consistent like Starbucks while offering more variety and more flavor. Lavazza Super Crema makes a pretty nice espresso and is cheap relative to high-end coffees.
Ehh, who cares what the snobs think? Drink what you like! I've been experimenting with coffee for like 2 years, and have found myself really enjoying dark roasted stuff (as well as lighter stuff!)
The truth is, you can get a really fruity single-origin bean but as soon as it goes into a latte, typically you've lost 99% of the origin characteristics. It gets a bit wasteful and expensive. Cafes typically go for house roasts that lean darker, and I can see why: they just work better in milk!