I have another notebook. My macbook pro. I don't intend on getting rid of it since it is so future-proofed for my professional needs. It's ready to add in more ram and whatever neat new 2.5" harddrives or SSDs I'll see come in the future. As SSDs rapidly drop in price, over the next few years, I expect to not only put in a very large SSD in my MBP, but also see battery life possibly improve with that upgrade.
It may be left a bit in the dust for any chance to run some new hot game coming out in a couple of years. But it will be my heavy lifting workhorse for some time.
I'm getting the MBA for the little powerhouse, that I intend to use an (outside of iWork stuff) generally start projects on there, but continue to finish them on the MBP whenever I have time to transfer. The general SSD size limitations pretty much keep me working that way. But boy is it portable. You can hide it between pages in some books. (At least the 11" one)