Breaking my no-chain-reviews rule once again, it was just nice that after a piss-poor experience at Umami Burger, we found the exact opposite when stopping in for some late night donuts at Winchell's. The crew is always smiling and the donuts are still fresh even in the late hours. There's not much to say, really. The donuts are tasty and the service is pleasant. That's all you really need to succeed.
Certain places should take a look and revisit their policy.