If you want a dark roast, check out the coffee place in kensington-not moonbean-that has a weird atomic looking sign in front. They roast thier own beans, which is critical to getting fresh, good coffee, unless you are going to roast your own. I find whole beans are going stale after 10 days or so.
Moonbean does mostly lighter roasts, even thier expresso. I prefer these. You might also want to check out balzac's in the distillery district. Pretty good too.
(I am a coffee snob BTW)