Political psychology is really very interesting if you know how to blend the two majors together rather than keeping what you learn in each course separate. Campaign strategist comes to mind as an applied career, or there is the academic route to conduct research.
You would also have all of the options of a psychology major (human resources, marketing, counselor, etc. - however, graduate school is necessary if you would like a decent starting wage) plus the options of a poli sci major. Psychology is not a difficult major, and none of the poli sci courses I took were all that difficult either, so I think the double major is certainly do-able.
If you want to pursue law, then it doesn't matter so much what you major/double major in, as long as you find it fulfilling and do well with the material.