Actually, it's best not to evacuate unless the authorities say you need to .... and that will involve primarily coastal areas only.
My elderly m-i-l was in Wilmington as Floyd approached so we were watching the storm closely. She doesn't live on the beach but, as the crow flies, it's probably only 3 miles or so. Nevertheless, we felt that she was ok to stay in Wilmington. A sister-in-law lives less than a mile from her and the family pow-wow-ed and decided that Mom would stay with s-i-l.
When Floyd strengthened so dramatically at the last moment and seemed to be taking a bead on Wilmington, the family all got on the phones and changed our decision. A nephew who lived in the Chapel Hill area went to get Mom and take her there and I drove down there to bring her to our home in Gastonia.
The total trip ended up taking over 12 hours ..... normally we can do it in about 5 1/2 going that route.
As I headed east on I-85/I-40, I had no problems ..... but as far west as Greensboro, the interstate was a parking lot with cars headed inland. People were going as far west as Knoxville, TN to avoid the storm. It created a very dangerous situation ..... if thousands and thousands of cars had been stranded on the highway during the full brunt of the storm, the effects would have been a tragedy of monstrous proportions.
The same sort of thing happened in SC but it was even worse. We heard tales of it taking people nearly 24 hours to get from Charleston to Charlotte! Cars were running out of gas as they sat idling on the highway. Those fleeing from the storm had no way to get food or water if they hadn't carried any in their car. They were having to answer nature's call in the woods along the roadway.
The vast majority of those people did not need to leave their homes. Ironically, many in eastern NC who fled wold have been ok had they stayed home ..... but because of the widespread flooding, they couldn't get back home for days. It was 5 days before I could take my m-i-l back home because all the roads to Wilmington were closed. Mom's house weathered the storm just fine ..... but the s-i-l with whom she was going to stay was flooded out. By the time we got to Gastonia that night, we had a phone message that s-i-l had had to leave her home as 3 feet of water had come pouring in. They were lucky .... they got back in the house right after Christmas ..... many people a little farther north in the state had to demolish their homes because the damage was so great.
The vast majority of those people took it upon themselves to leave the area. Emergency officials only issued mandatory evacuation orders for the immediate coast ..... the beaches and sounds. Floyd seemed to have the strength of Andrew and the size of Hugo and people fled by the thousands .... into a potentially much more dangerous scenario.
x42 contributed to the panic by declaring areas along the east coast disaster areas long before Floyd even made his mind up where he was going to make landfall. That spooked people even more than usual.
Unless you have unusual circumstances (health concerns ... live in a low-lying though inland area prone to flooding ... some other such such special consideration) listen to your local emergency officials. They know what areas are most at risk ..... they've been there, done that before.