I actually like the staff at Clementine a lot, but that's about it for them. You're right about the coffee kind of sucking. Epoch on North Loop has become a replacement for Clementine for me. Much bigger space, much more personality in the atmosphere, and better coffee.
The Costco coffee I had at Quacks on 38th st. was really the worst I've had here in Austin. It was really really awful.
Anyway, on a positive note, I'd like to list the best cafes I've been to in Austin.
As far as atmosphere goes, Austin cafes are somewhat lacking, but The Green Muse on Oltorf has been great for several years. Also, Epoch on North Loop has a spacious yet cozy feel to it--huge bar, plenty of indoor/outdoor tables, and a deco-esqueness that I like.
The best espresso I've had was either at Ruta Maya's or Little City on Guadalupe (RIP). Both roast their coffee in house. Also, I'm surprised no one's mentioned Texas Coffee Traders on E. 4th for getting fresh beans. They have a knowledgeable and helpful staff and dozens of different fresh beans and blends.