I just upgraded to WordPress 3.8 and decided to stay with my trend of using the default themes when possible.
I did setup a Twenty Fourteen Child Theme so I could make modifications. The only change I made so far is to the footer file so I could add my copyright.
The main idea is that I want my site to be flexible enough to change easily and being able to switch to the default theme at any time pretty much assures me I have everything set to make easy changes.
This was the easiest change I have seen when it comes to using the theme that ships with WordPress. The only real change I needed was to go into the Menu option and save the location of the menu. Previously that was a little more work and required rebuilding the menu.