If you have two days, keep one for just spending in Sorrento _ the day with less time).. Sorrento has great shopping and the other day do the Amalfi coast tour..( Marcello)..
it is so much fun..
You don't need to waste alot of time in Positano or Amalfi at the tourist shopping spots as they have all the same stuff in Sorrento ( for less) and that time should be saved to see the beautiful coast and have that memorable lunch.
Want to go back now!!!!