We're Matthews residents and have been going to Souper Salad for the past 7 or 8 years. It's always very busy there...a sign of a successful restaurant.
If your children aren't really "into" salad, there are plenty of other options....a taco bar, potato bar (with all the fixings), pizza station, etc. They shouldn't have a hard time finding enough to eat.
Every time I've been there, it's always been clean, safely prepared, and well-staffed.