The easy heuristic here is approval voting: award one point to a subject each time someone mentions it as a "nice to have", and 2 or 3 points to each "essential

The easy heuristic here is approval voting: award one point to a subject each time someone mentions it as a "nice to have", and 2 or 3 points to each "essential", then tally up the votes to get a ranking. Truncate it at four years' worth of classes, and you have a curriculum!