I've been fairly impressed with Meshmixer...it seems to give you a nice amount of control over smoothing and reducing resolution interactively, and it has some nice repair/solidifying functions. I've re-imported and re-textured in Photoscan with nice results. It doesn't seem to choke too heavily on dense geometry, either.
One drawback of Meshmixer is that you seem to lose your imported texture once you start refining the mesh, it just turns to a flat shade solid color in those areas. It's also somewhat buggy, although not as much as Meshlab. (at least in MacOS)
I wonder what it will turn out to become as a final product from Autodesk, though...pricing, etc.