In terms of hiring, most employers don't actually understand the difference between a dual degree, dual major, major/minor combo, and so on. So in my honest opinon, study what you want to study. A minor, dual, or 2nd degree generally looks good, but one doesn't look any better than another in terms of "hire-ability."
As an undergrad, if your looking to go into business, study electrical engineering or finance (Companies will generally help you, or fully pay for your MBA, so there is no reason to study business twice). If your looking to go into the medical field, especially on the "pre-speciality school" courses, humanities is always a safe bet (assuming you complete the pre-reqs for the specific type of secondary school your interested in).
Career Center Adviser,
Rensselaer Polytechnic Institute