For most races, I've sat in the Bill France Tower because I waited too long to get my tickets. However, the France Tower is extremely comfortable and easy to reach. I've sat as low as row 3, and still enjoyed a pretty good view of the track. The picture on this page is the view from section B4 Bill France Tower Row 14. Really, counting qualifying, I've been around most of the track, and I've never found a bad view.
Parking can be tough.
Most people park in a huge field north-northwest of turn four. The parking lot isn't paved, so a rain will definitely get you muddy. Because of this, I try to arrive at the race at least four hours early and look for a parking space close to the perimeter of the lot. It's taken me about three hours after the race to get on the road. If you want to go south toward Greensboro after the race, you'll first have to go north and search for a place to turn around.