I've tried most of the available ultrabooks, unfortunately none have decent keyboards.that's what I wonder too.. if I ever bought an MBA or an ultrabook, would it make the ipad keyboard combo obsolete for my own personal use
If I were to make a suggestion, all things considered there's only 2 laptops worth buying. Either a 11" or 13" MBA. I've used both ThinkPads & PowerBooks, MacBook Pros for years. ThinkPads had the best keyboards hands down, with Apple a very close second. Recently with Lenovo moving to the same chiclet style keys as Macs & VAIO's , there's no longer a difference between them. Where Apple truly excels is the huge glass trackpads that now come on all MBA / MBP machines.
The 13" MBA is my favorite between the two sizes (I bought them both since I couldn't decide after the in-store experience) the top row of keys being larger. Since it's footprint is just one inch wider & not much deeper, I prefer it over the 11" not to mention the larger display & slightly greater key pitch despite Apples specs saying they're the same. These are the things you notice when you own them both and spend the kind of time it takes to discover the little things.
I've had an unbelievable number of new high quality laptops over the years from most major manufacturers, and what it's afforded me is the depth of experience to truly appreciate the overall excellence of the 13" MBA. It's as much about what it doesn't have (minor annoyances) as what it does have.