[AnimalMuppet]

I think of languages as a multi-dimensional tree, with branches extending in different directions. I think that the trick is to figure out what the yak-shaving aspects of the project are going to be (which you can think of as a vector), and picking the language that goes the furthest in the direction of that vector (and thereby does the most to minimize the yak-shaving). This requires that you be able to fairly accurately determine what the yak-shaving will be up front (which can be problematic).