I wrote my senior thesis on a calendar assistant that achieves much of the functionality mentioned here (recommending times/places, auto updates, etc) and lost so much motivation just to the sheer amount of integration between parties/services required to solve this problem. There has been a lot of work in the academic space on optimizing calendar/email functions but its challenging to implement across so many email providers/clients. I'm glad Google is taking a step in this direction, I'm not confident many startups would be able to solve this problem effectively.