I currently own or use a variety of Macs, and am approaching the end of a 'cycle' of Mac usage, where I need to decided what Mac I'd like to purchase next. Currently, I'm using a 27" iMac at work, an 11" MacBook Air (from work) for travel, and a 24" iMac at home. They're all great computers in their own right, and using Dropbox, MobileMe, and a couple other helper services, I can operate simultaneously on all three Macs, without any hiccups.
So, I'm thinking about getting a new Mac for hardcore development work (web and app), some graphic design, and possible portability. I have an iPad for lighter computing (reading, browsing, email, videos...), so even though the MacBook Air is probably the best thing to happen to a laptop in a very long time, I'm shying away from it as my primary personal computer.