I have docs to go full version and while it works fine on the Xoom I wouldn't call it tablet optimized.
Honestly if I had to do it over again I would spend my money on Quickoffice. The reason being that DocsToGo for android is a generation behind what they offer on iOS (they have a true tablet version for it) and since they got bought by RIM (blackberry) I'm not sure how much effort will go into development for Android. That coupled with the fact that we have already seen the tablet optimized version of Quickoffice (full version should be out soon) and it actually looks pretty awesome makes me regret my decision.