Kings! Stallings Road, either in Indian Trail or Stallings.
There's one on Monoe Rd close to Cotswald - Banner.
and Southern Styles on Rea Road. Those are my picks for the best in Charlotte!
Lisa

diggerb2,
where exactly did your niece settle here in the Charlotte area? It's rather LARGE and spread out.
If she's situated in North Charlotte area, she's not likely to travel to Lisa's and my favorites in South Charlotte.

If your niece is locating closer to Uptown Charlotte then
Roundtree (rountree plantation) is very well established long time with much of their plants in greenhouses or under cover and very well cared for.
Of course, tell her to sign up here on Garden Web.

she's near carowinds theme park on south side-- that's the exit you take off 77 and then head westwardish.

Ok, google 'Sugar Creek Garden Center'
It's just over the SC line so listed as Fort Mill,SC but they do have a website and they do offer gift certificates.
A bigger hike for her would be Rountree Plantation but not difficult for her to find and worth the trip.

diggerb2, if she's at all interested in gardening and plants I really think Rountree Plantation (on Sholtz Rd off of Old Pineville Rd) is the best. They are growers, umpteen greenhouses and most of the employees have been there for years so lots of advice with experience. Google that one too and see if they offer gift certificates/giftcards.