If you want to know how large your uploaded files are in Google Docs, sort by Storage used to see document size.
Word documents, Excel spreadsheets, Powerpoints, PDFs, images and any non-native documents all take up storage space in your Google Docs - basically anything you don't convert. With only 1GB of storage space available on standard Google Apps for Business licences, it's advisable to keep track of the size of documents you are uploading.
To do so, use the Sort feature and select Storage used. Your documents will be sorted by size and the size of the documents you own will be shown. Since this sort prioritises non-native documents only you own, it's also a good way to find documents you have yet to convert.
Try out the Sort dropdown, you can also sort by last modified, opened, title and priority - let us know what you think of this feature in the comments.