CloudExtend Gmail for NetSuite users can attach emails and file attachments to NetSuite records thus giving everyone in their organization 360 degree visibility to import communications and files.
If you're concerned about document portability and/or storage space in the NetSuite file cabinet then consider creating a Google Drive folder for each of your NetSuite records. For example, you could have a parent Drive folder called Customers and then a unique sub folder for each customer.
Using CloudExtend's Google Drive feature you would then attach each Google Drive folder to the specific customer record (a one time process). Moving forward, any files you save with the native Gmail 'Save to Drive' icon to the customer folder will automatically show up in NetSuite under that customer. You can even get started by doing this in a bulk operation.
See it in action in the video below.