How to properly design multi-orientation iPad application

What's the correct way of designing multi-orientation iPad app nowadays? I've read a lot of Apple docs, web resources and some SO Q&A. Here are my initial requirements:

• This has to work on iOS 5 and above. No need to create back compatibility with previos versions of iOS.
• I would like if possible to have portrait and landscape UI defined in different NIB files.
• My NIB files will have different images for same UI elements in different orientation (like I will have header.png and header-landscape.png UIImageView for example.
• App will have several screens and I need to be able to switch orientation on each of them.

So what do I do?

• Create one VC per screen and replace underlying view in willRotate handler?
• Create one VC per orientation? But then how do you switch them properly?
• Simply re-arranging elements won't work (I think) because I would have to reload images.
• Write everything in code (I would really hate this idea)?

What are proper approaches to this issue as of today?