Once I got started planning in google docs spreadsheets I found a huge raft of pluses that made it easier to plan in spreadsheets than in a document.
The fabulous merge button found in google docs spreadsheets
One of the biggest pluses was being able to merge cells to create larger spaces within my planning. Another bonus being the ability to use the same document for a term or year by using new sheet tabs along the bottom.
Our team has also created our class descriptions in this manner - allowing us to break up certain parts of our class description to make it more easily accessible for certain parts of the information we gather.
Another great feature of using google docs for planning is the ability to merge all your documents together on a google site with ease. It allows you to easily click once to embed a document into the page you want. For ease also allows you to quickly click out to the editable document from a link at the bottom right corner of the embedded google doc.
This link will take you to an example google doc for a yearly overview - you are welcome to make a copy and adjust or use how you need to. It shows simply what is able to be done with your planning via a google doc spreadsheet.