Hi! I live about 2 hours from MB and go several times a year. There is a lot to do there, depending on what you like.
If you want to do some major shopping, go to the Tanger Outlets (the ones on Hwy 17 - don't even bother with the outlet on Hwy 501!).
You can also go to Broadway at the Beach or Barefoot Landing. Both have a variety of stores and restaurants. Broadway also has a movie theater and a miniature golf course.
One the most fun things to do is to drive up the "strip" (Ocean Blvd) at night. Ton of people there and lots to see. This is one of the things that may depend on your age and personality
This is mostly the under 25 crowd.
If you want to drive south a little bit (maybe 15-20 minutes from central MB), you can go to Brook Green Gardens, which is a really neat place. Lots of beautiful gardens, fountains and some animals/birds.
If you have any questions, please don't hesitate to PM me!