The BID does several things I know of and probably a lot more.
They have the clean and safe team which you will see wearing yellow shirts around the downtown area. They will help people with directions, keep homeless from sleeping in common area, escort people to places if the people feel threatened, and keep downtown clean.
They help the recruitment of companies coming to downtown. I know they played a critical role in bringing the insurance co Trumbell Services to Main St.
Promotional events like the Magnolia Market, Movies on Main, and I know they are helping out with the car show on Main St the weekend of Aug 20th.
I am sure if you contact them they could provide you with a list of what they do. The website for the BID is www.citycentercolumbia.sc
Now here is a few more ideas:
How about a sporting event or tournament downtown with proceeds going to a charity. Ideas such as a wiffle ball tournament, street soccer, go-cart races in the street (Bloomington, Indiana has a killer race), or maybe a beach volleyball tournament if you could get the sand out pretty easy. This would attract families and people from other areas of the state. Half the battle with Columbia is it still percieved as it was in the early 1990's. It is far from being great but it is getting better.