How helpful is a Latin honors designation (cum laude, magna cum laude) for admission to PhD programs?
The honor designations carry essentially no weight. The additional honor program requirements, however, could carry substantial weight. If for example, one of the extra requirements was an independent research project, this would be very valuable for graduate school admissions. If the requirement was the completion of a university breadth requirement (e.g., basket weaving), then it has no extra value for admissions.