All expenditures stimulate the economy equally, as measured by the "marked bills" theory. That means the only way to compare them is to evaluate opportunity costs. Spending a million bucks on constructing a big hole in the middle of nowhere, and performing an important infrastructure revitalization, will both put dollars in the hands of laborers, and thereby grocery stores and so on, at the same rate. That's why all of the useful parts of the discussion are on the specific, immediate consequences; the distant consequences are the same no matter what you do.