What positive contributions did the industrialists of the Gilded Age make in the United States?I am trying to look at the positive things the great...

The first thing I would talk about in terms of positive stuff done by the "robber baron" types would be their charitable works.

The most famous of these charitable works, perhaps, was that done by Andrew Carnegie who had gotten so rich in the steel industry.  He contributed, for example $60 million (that would be worth a LOT more today) for the building of public libraries (source: The American Pageant).

Second, the industrialization these men led helped make America a lot richer and, eventually, increased the standard of living of the average American.  For example, the GDP per capita in the United States in 1870 was $2457 (in 1990 dollars).  By 1913 it had more than doubled, reaching $5307.  This shows that the US was getting richer during this time.  And that was driven by the industrialization.  (Source: "History of the American Econom," by Walton and Rockoff)