HP Chromebook 14
HP's Chromebook 14 is $299 (Wi-Fi) and $349 (Wi-Fi and 4G). The latter includes free 4G data service from T-Mobile, up to 200MG per month for two years. Both models (released October 2013) have a 14-inch display, the largest of current Chromebooks, and come in three colors. Based on Intel's Haswell architecture, HP's Chromebook battery reportedly lasts up to 9.5 hours, the longest of any Chromebooks. Weight: nearly four pounds.
(Author's note: I've tested an HP Chromebook 14 and think it's a great choice for mobile professionals, if you don't mind the weight and you can deal with the pastel blue and peach colors (white is another choice). The free 4G service from T-Mobile is a compelling benefit as well.)