Hi,
I was on hols in Sorrento, Amalfi, Positano and Ravello in Sep, so its all fresh in my mind!
The drive from Sorrento to Ravello will take about 1.5 hours. On the map it doesnt look that far, but the road is a very narrow and twisty right on the edge of the cliff so you have to go pretty slowly. Also the view is just amazing, so you'll prob want to go slowly to take advantage of it!
At night driving back from Ravello to Sorrento could be a bit hairy if you are not comfortable driving on the other side of the road (at least on the way back you are hugging the cliff face and not the cliff edge!!)
Amalfi and Positano are very steep villages, right on the cliff edge. Ravello has a lovely piazza with a church on it, and feels more spacious than the other two. Sorrento seems the biggest out of all these villages, and is where you get the boats to Capri and Ischia.
We stayed in a little village called Santa Agnes nei Due Monti (or something like that!) which is near Sorrento, but right on top of the mountain, so you can see the sea on both sides of the peninsula - a really picturesque place!
Enjoy the hols!