MVVM Light + Unity or Prism?

I am a little out-of-date in WPF right now and would be interested to hear peoples opinions on the latest version of Prism (which I used a couple of versions ago) vs an MVVM Light + Unity approach (which I have never done - decent examples URLs would be good).

My project will be a large one comprising multiple modules written by several developers. There is also the funds to bring in a 3rd party control suite in order to set up a nice workspace using one of the fancy Docking/Workspace layout managers out there (and I know some play better with the Prism regions than others).

If you were starting a project from scratch right now, what would you go with and why? Details on specific recommended architecture patterns would be useful (e.g. auto discovery of module dlls? Injecting logging service?). Basically, any thoughts and advice would be good. I'd like to get a good discussion going. Perhaps there is another direction entirely that you would suggest going in? I'm very much in the research phase and would like as much input as possible.

I put this on here because I thought it would get less biased points of view than the Prism/MVVM Light forums but, if there is a more suitable place for this question, please point me in that direction.