A way to say where I 'need' to be for various times during a trip (pre-planned events, arrival/departure times + places, any business meetings), and then to have suggestions for things to do in the between-times and spaces.

In other words, it's a routing problem - I have these fixed points in space + time - what interesting things/events exist in-between those and are routable?

(also needs to allow sensible amounts of time for food breaks, lots of buffer time to enjoy the surroundings, etc)