Sorry AMCarter3, my bad. While it used to be in GoodReader they apparently removed it some time ago, supposedly for some legal reasons?
I too use GoodReader primarily with dropbox and box so had not noticed it was gone.
As an aside, for those apps that support iCloud storage, if you have a Mac, enable Documents & Data in the iCloud control panel. That will make a folder on your hard drive, named "Mobile Documents" that is your local mirror of your iCloud folders. Apps that sync their content to iCloud will make a folder for themselves when they first conntect to iCloud, and that folder will in turn get created as a sub-folder in Mobile Documents on your Mac (I still have my one for Goodreader, "JFJWWP64QD~com~goodiware~GoodReader", along with ones for Pages, Numbers, and a host of others).
You can then drag and drop any file you wish into that folder (as long as it is a file type supported by the app), and they will then sync to iCloud. You then use the app and download them for use on your iOS device from within the app. That folder on your Mac will be updated whenever it changes and your Mac has internet access to iCloud.
But, for PDFs in Goodreader, yes, dropbox works great, and has their free companion app for OS X if you want things on your computer to sync automatically too.