How much thrust and fuel are required to get a B767 moving from a complete stop?
This research paper may be of interest for you. According to their data the 777 burns about 250Kg of fuel on taxi on average with a few data points showing burns well over 700Kg of fuel. This paper which quotes the previously linked paper talks a bit about different fuel saving methods and their impacts, like single engine taxi and what not. In short taxi distance will always burn a bit more fuel, the primary concern is taxing for takeoff (since you don't want to cut into your estimates). Once the plane is back on the ground it becomes less of a safety concern as running out of fuel becomes an inconvenience (that a tug can solve) and less of flight risk.   

Here is an interesting paper on fuel burn rates if you were to extend a runway by 500Ft. They provide data/estimates for many air frames.