Elizabeth, I agree with Mark. A PhD is not common in the business world. A bachelor's degree is all that is required. Having said that, I am an advocate of earning a masters. I earned an MBA and believe that it helped prepare me and accelerate my career.
As for the PhD, some of my MBA classmates went on to earn PhDs, but did so with the intent of teaching business at a university.
Great question. In my experience, i do see increasing levels of education achievement these days versus prior years. Both Brian and Mark hit the nail on the head though. A bachelor's degree, in may instances, will be required. I do highly recommend pursing a MBA track though my personal recommendation is space it out slightly after your BA. Getting some post graduation experience before embarking on an MBA course will best set you up for success.
Best of luck on your endeavors.
It depends on what type of business and industry you wish to go in. My experience is that most people in business have a bachelor's degree and quite a few in upper management have a masters. Most business areas do not require a doctorate. If you are in a very specialized field or need to show a very specific expertise then a PhD would be helpful. PhDs are usually required when someone wants to work in a university setting either in higher management or as a professor.