I got a Lenovo T440s last fall to help me finish my b-school apps when my old laptop crapped out on me. I see that it's just over $1k, but if you're current employer has a corporate discount program or anything you should be able to get it under $1k.
I've also seen a lot more people using Microsoft Surface Pro's in lieu of full laptops. I've actually heard some good reviews on it's capabilities as a computer and a portable touchpad. I know that with various configurations they can get really expensive, but it might be worth the investment.
Other than that, I think the ultrabook class of laptops is great for extremely portable and extremely capable computers in general. My only suggestion is to be wary of Acer. The laptop that crapped out on me was an Acer and although it was great while I used it, the screen absolutely stopped working about 12 months in and then 4 months later it completely stopped working. I think the battery failed. The durability and quality of the computer I think is what ultimately caused it's doom.