I've posted this before, both in 2009 and 2010, but it's been a while and the point remains valid. I see way too many people worry about the actual document of their thesis as their grad career drags on another semester. Get the papers out. Don't create a tome for a shelf.
Whether it's tradition or a lack of well communicated expectations, grad students seem to be enormously focused on The Thesis. Students fixate on this document for months before writing it and then for weeks to months of actually writing it. I have to say, I've never quite understood that, because if you had to put odds on the people who will read your whole thesis it would look something like this:
10:1 Over-eager new student who takes on aspects of your project when you leave
1,000:1 You, after it's done.
100,000:1 Your parents
1238947692092y47nc783et687:1 Everyone else
When I got my thesis back from the binders, I opened it up and read the first sentence. In that sentence, I had a typo that made the word "three" into "tree". Seeing that, I promptly shut the thing and that was that. Never opened again.
The one caveat to this is if you never publish the papers. In that case, the community might find it and someone might crack it open, but probably not. But that's the point. Uncommunicated science might as well never have been done in the first place. Get the papers out. Don't focus on an arcane document that will gather dust for the next 50 years until the departmental office needs space and throws the old ones out. Write the papers, or at least write the chapters as papers so you can get them out quickly after the thesis. If you publish before you graduate, writing your thesis should be about as simple as slapping together a half-assed intro and conclusion (complete with typos that no one catches) and be done with it.