Over the past few weeks, I've been using the ASUS Zenbook UX31 ultrabook. This has to be one of the thinnest laptops I've ever used.
From a distance, ASUS Zenbook UX31 looks like a MacBook Air, but this is a Windows PC running Windows 7 and it lacks a backlit keyboard. The MacBook Air actually went through an interesting transition for a period where Apple eliminated the backlit keyboard in the second generation, then brought it back in the third generation of the MacBook Air.
I personally think that a backlit keyboard is an essential feature for health care professionals and business executives. You're likely to find yourself working in a place where the lighting is low (radiology suite, an airplane at night, etc.), and it really enhances your productivity when you can see the keyboard.
The ASUS Zenbook UX31 also uses a proprietary power supply that is unlike most standard power supplies. This means that it will be more difficult to find an external battery pack or a universal power adapter to power your ASUS Zenbook. The battery life on the Zenbook is rated as 5 hrs and 58 min by Laptop Magazine and 6 hrs and 9 min by PC Mag. When PC Mag reviewed the ASUS Zenbook UX31 last November, they have it the "Editor's Choice" recognition. Then, in Jan of 2012, they gave the "Editor's Choice" to the HP Folio 13 ultrabook.
Overall, the ASUS Zenbook UX31 is an excellent choice for someone who cares deeply about the aesthetics of a laptop. It's super slim and light. Most people will think it's a MacBook Air (which is a compliment to Apple).
Be aware that this notebook does not have a VGA port. So, if you frequently give presentations, you'll need to carry an adapter. Plus, the HDMI port is actually a mini-HDMI port on the Zenbook, so you'll need a different type of adapter if you plan to attach to a standard HDMI cable.
If the ASUS Zenbook had a backlit keyboard and longer battery life, that would really make it a top-notch ultrabook. I hope to see those features in their next model.