Are you set on Wilmington, or just the area? Just south of Wilmington is Carolina/Kure beach, you can drive out on the beach on the north or south side, $20 per day IIRC. As far as a quiet beach, I prefer going down a little further south to Oak Island, it is a lot slower paced and more family oriented, so not much nightlife except Dairy Queen, but the beach is great during the day, especially if you drive down to the point. Southport is between Oak Island and Carolina beach, there is great food there (Provisions) and a great small downtown to walk around. There isn't much of a beach there, but you can take the ferry from there to Ft Fisher/Kure/Carolina beach. We usually stay in OKI, then go up to SPT for a day to walk around/eat, and then usually will make a day out of taking the ferry to Kure to drive around on the beach/fish/enjoy the peace.