I want to get a MBA at a top-tier business school but I do not know what to major in or if a double major would look good. Any suggestions?
It doesn’t matter what you major in; you can go to a top tier business school with any major. Virtually all top-tier business schools are going to want you to have at least 2 and preferably 3-5 years of work experience before you are admitted, anyway, and your work experience is going to be a large part of what gets you admitted. The most popular majors for MBAs are business and economics majors, although that makes a lot of sense given that people who are interested in business school have probably been interested since they started college. After that different MBA programs have different distributions - at some, physical and natural sciences majors are the next most popular group; at others, social science majors are the next most.
Double major if you are interested in two majors equally, and want to study them both. It doesn’t necessarily “look good” or impress anyone if you study two majors, but it’s not a bad thing either - it’s pretty much just a net netural.