We skipped the Capri grotto. That was mainly because we had already enjoyed the (a ?) Croatian grotto (from a small cruise ship, so it didn't take all day), and also because of the time-consuming nature of the Capri grotto. Lots of people skip it because there is so much time-consuming (if, pleasant) walking on highly pedestrianized Capri.
Our car-and-driver for the Amalfi Coast (240 euros, 8 hours from our hotel in Sorrento) recommended the Green Grotto, and it took little time (since we were in a car anyway, and didn't have to park it) but I agree that it is quite missable. We did not do "The Path of The Gods". Have you looked into that? How come you didn't mention Pompeii?
I don't think the Amalfi Coast is overrated, but I think that some visitors may overrate certain things. For example, how many of the same international clothing boutique chain do I need to look into the window of? Is a shopping strip nicer just because it's on a lovely island? Let me confess that one of my must sees was the hotel La SIreneuse, which is a famous upper-crust destination. We had to sit in the non-guest part of the bar for our outdoor drinks, and we enjoyed the view. But I'm glad we didn't spend the money necessary to sleep there. And I (very personal opinion) do not need to sleep on the A.C. As an East Coast USA resident, and frequent Caribbean visitor, I'm not impressed by the crowded stone pebble beaches and cold water. (I'm not slamming the AC, just responding to your question.)