Double majors and majors/minors that overlap are the easiest to complete, as there are many common courses so it may not extend your time in school. However, they may not make a huge difference in the long term. For me, what worked well was minoring in something completely different from my major, that highlighted a valuable skill that differentiated me from others in my major(s). I was a double major in Math/Computer Science, and a minor in Communications. The double major was not really a big deal as this was back in the dark ages when Comp Sci was often part of math departments. The Communications minor was of interest to employers (and surprisingly enough continued to be 20+ years later), as it showed I was a geek with writing and presentation skills. Not necessarily skills that commonly go together, but a combination that offers great potential.
Combing a STEM major with some type of humanities minor is often attractive to employers as it shows you are more well-rounded than the average STEM major.