Dreamweaver CC Design view = a mess

Design View has never been swift at rending advanced CSS.   If I'm working with a complex layout and a lot of content, it's sometimes simpler to work with an unstyled page.

Go to View > Design View Options > Style Rendering.  Turn off Display Styles.

This won't effect  Live View,  Real-Time Preview (F12) or Right-Click > Open in Browser.

Nancy

The newer versions of DW are more prone to display problems when they run into errors than older versions were.

It's possible you have errors in your html that are confusing CC more than they confused CS6. It might be worth cleaning anything that comes up in the validator at http://validator.w3.org/nu.

But it's more likely Design View just can't render your page.

After CS6, Live View was given some rudimentary editing capabilities. Some things still aren't there, like Image Maps, but you can do a fair amount of editing from within Live View now. I'm pretty sure Adobe plans to eventually remove Design View at some point, but the Live View Editor isn't robust enough yet.