If you want to do a streetcar ride for cheap sightseeing, get on the green one and go up and back down St. Charles, not the red one that goes up and back down Canal/Carrollton.
Green one will take you to Tulane's campus (and Loyola, which is right next door). Go do that. The campuses are sweet, and Tulane's stade situ is pretty unique. New, small, strange football stadium, incredibly old but charming tiny basketball gym, and a pretty sweet college baseball stade. Also, the front entrances of Tulane/Loyola are right across St. Charles from Audubon Park, which is glorious. (Nature and/or Family fun alert!)