In Which Courses?
Although many schools look only at your cumulative grade point average in determining whether you are a presumptive admit or presumptive deny, most look at your transcript more fully to evaluate the major or the overall difficulty of your course work. In general, the majors that admissions officers like best are philosophy, English and history. These majors tend to emphasize analysis and writing, which are essential legal skills. Most other majors are considered more or less equal, with a few exceptions.
Majors vs. Courses
Most schools review the entire transcript, especially if you are in the discretionary range. They are looking for diversity and difficulty of courses; they want students who have challenged themselves. Most schools frown upon "pass-fail" courses; one or two won't hurt you, but more can lead them to question your willingness to push yourself in difficult subjects. They also want to see courses above the introductory level in subject areas outside of your major. They will look for courses which seem too easy (Indiana's "History of the Comic Book" comes to mind), and those which challenge your thinking and writing ability.
It is my experience that double majors are worth little, if anything, in the admission process; take them to satisfy yourself, not to impress the law school.
Science and Math Majors
Hard science majors (biology, chemistry, physics, engineering, sometimes computer science) are considered difficult majors, and law schools may allow quite a bit of leeway on your gpa -- sometimes more than half a point. But these same majors may raise questions about the extent to which your verbal skills have been honed; try to take a few extra liberal arts courses if you are a hard science major. Accounting majors are viewed with very mixed regards. Some people view accounting as a trade rather than a profession, and hold little esteem for degrees in this area. Others see it as requiring discipline and analytical skill, and consider it appropriate prelaw preparation.
Majors which tend to be looked on with disfavor are those which emphasize creativity instead of analysis, such as dance and communications; admissions officers say that transcripts loaded with these courses give them little to evaluate. Surprisingly, most admissions officers like music majors, recognizing both the discipline necessary to performance and the intelligence needed to grasp formal music theory. Like science majors, you should try to add a few classic liberal arts courses to your transcript, to exhibit your writing and analytical skills. For artists, art history will often serve this purpose.
Criminal justice, prelaw and paralegal courses are often viewed with disfavor, both because they are viewed as "soft" majors and because people with these majors often think they already know the law. As a result they don't take law school seriously enough, and often have poor grades.