Columbia [1] is an easy city to get around in and enjoy. Reserve a half-day for the Riverbanks Zoo [2] and a minimum of another half-day for the other major sights. The best way to enjoy the city, however, would be to have a couple of days. This will allow you to see more of the city, including a night out in the Vista and an evening in Five Points.
Because of the physical breadth of the Midlands [3], one day is not nearly enough to enjoy the rest of the region outside Columbia. You should reserve a half-day alone for Congaree National Park [4], for example. If you only have a day or a day-and-a-half, choose between two areas: either the Pee Dee [5], with stops in Camden [6], Cheraw [7], and Hartsville [8], or Santee Cooper [9], with stops in Orangeburg [10] and Moncks Corner [11].
Links:
[1] http://www.moon.com/destinations/south-carolina/columbia-and-the-midlands/columbia
[2] http://www.moon.com/destinations/south-carolina/columbia-and-the-midlands/columbia/sights/riverbanks-zoo-and-garden
[3] http://www.moon.com/destinations/south-carolina/columbia-and-the-midlands
[4] http://www.moon.com/destinations/south-carolina/columbia-and-the-midlands/outside-columbia/congaree-national-park
[5] http://www.moon.com/destinations/south-carolina/columbia-and-the-midlands/the-pee-dee
[6] http://www.moon.com/destinations/south-carolina/columbia-and-the-midlands/outside-columbia/camden
[7] http://www.moon.com/destinations/south-carolina/columbia-and-the-midlands/the-pee-dee/cheraw
[8] http://www.moon.com/destinations/south-carolina/columbia-and-the-midlands/the-pee-dee/hartsville
[9] http://www.moon.com/destinations/south-carolina/columbia-and-the-midlands/the-santee-cooper-region
[10] http://www.moon.com/destinations/south-carolina/columbia-and-the-midlands/the-santee-cooper-region/orangeburg
[11] http://www.moon.com/destinations/south-carolina/columbia-and-the-midlands/the-santee-cooper-region/moncks-corner