If i was going to miss anything out it would be the last few sections.
Start from the visitors centre and ride up, The black around dixons hollow is good fun, and there is still plenty of the old black sections/off piste round there to explore.
If you run out of time there is a road straight down the middle back to the visitors centre to the car park. Or take the blue route from Riggs and Dale.
There is loads of good riding in there,
The guys/girls in pace will be able to give you some good info.