For those of you who are having trouble using that gmail to google drive script because it is putting your books in the wrong folder, there is an easy workaround by adding 2 lines to the script that tells it to use the folder ID instead of the name.
Step 1: Open the folder you want the books to be stored in. For me this is called books. From the address bar, copy everything that comes after "folders/"
For example, mine is "0B5iGhZr6jmEtMS01Yjg5Y2VkYy05MTNiLTQxZTAtODM1Yi1j NGZiZjllODhjODQ"
Step 2: Open the send-to-google-drive spreadsheet. Click "tools -> script editor"
Step 3: Add a line under "var gFolder = ..." which says this:
var folderId = 'YOUR FOLDER ID';
Step 3: change the line which says var folder = DocsList.getFolder()
var folder = DocsList.getFolderById(folderId);
Step 4: Save.
Reinitialize the script, and you should be good!
Of course, now the field in the spreadsheet won't change anything anymore, but it doesn't really matter since you are probably only using this to send things to your kobo!