lots of traveling for me (design/build).. i have a macpro as the main computer but the laptop sees just as much, if not more, real otj work..
15" i7 arrandale
rhino3D, sketchup, layout, numbers, photoshop, indigo (well, setups and/or in a pinch renders.. i use the desktop for the real deal)
(then some other apps that see a fair share of use -- mail.app, safari, ishowu, itunes, pages, automator, preview, dictionary, address book, keyboard maestro, ical, quicktime7, vlc)
fwiw- i waited for arrandale in hopes of getting a good priced 17" c2d.. finances weren't working out properly at that time.. ended up picking up a refurb hirez 15" last november.. i couldn't be happier-- this is one sweet machine.. it just kinda gets out of the way and lets me get the work done.