We had an interesting but "un-resolved" discussion recently within the team regarding header design (logo + navigation links etc) for a web application. I would like to know if having a dark or visually separate header (Eg: emc.com, imdb.com) help the user get confortable with the website easily when compared with headers which seem to merge with the content area (eg: amazon.com, mint.com).
In my point of view the header should stand out in contrast of the content. Keeping the header clear and simple makes it much easier to find out who the site belongs to and what you can do there. If you compare Usability First to Amazon website - I find Usability First easier to navigate. Amazon takes much longer to understand and luckely they have a huge search area in the top center which I always use. I wouldn't dare trying to navigate to what I wanted on Amazon. But that's me, others might find the navigaton better.
Usability First says this on Information Architecture:
is much more clear than the following
The header is supposed to divide content - and throwing in a horizontal rule below a bigger font makes it easier to read - doesn't it?!
The question can't be reduced to a visually distinct header.
The rule of thumb for navigation controls is the same controls in the same place throughout the site.
A visually distinct navigation menu helps the user recognize the controls, and tell apart content from navigation.
Whether it should be distinct is usually determined by esthetics more than functionality. Functionality-wise, I would recommend to:
use a distinct navigation header if content is colorful, rich, or in another way looks very distinct on different pages.
avoid a distinct navigation header if there is no clear separation between navigation and content.
None of these explains the difference between the samples oyu provided, though in those cases I personally do feel more comfortable with the distinct navigation header.
All users are different - so you might find some that like or get comfortable with one type of header and some gravitate towards another. So if you are really wanting an answer via the users opinion maybe try some user test cases and drive test users to some different headers and ask their opinions and get feedback from the true source. As I said, it depends on the user - I know some people who hate colorful patches on websites because it distracts them and I know others who love them (like me) as it can drive the users eye to what you are trying to do for them.