I would love to be able to set a specific folder in Google Drive as the default folder for a project. That way I can easily access all docs inside, create new files directly into that folder and also narrow the view for my clients to access only the files relevant to their project.
Teamwork does this very well. Not only can you determine the specific folder per project, you can also set the privacy settings as to who as access to it.
I can also allow my clients to upload files directly into that Google Drive folder (right inside the project in Teamwork). That makes it really easy for my clients to see everything in one place.