Have a 17" 2009 MBP which is becoming to big for me as I am having to travel more now I do not do anything to serious on a computer anymore mostly email web browsing spreadsheets. I am trying to decide between a 13 air or 15 pro purely for screen since I have gotten used to the higher res of the 17 I just don't if it is worth $650 for 2 inches more of screen?