We are planning on two weeks in Greece including Nafplio, Athens, Paros, Hydra and Santorini. As I’m trying to plan out days, I’m wondering if most/a few/some retail establishments close in the afternoon? Can you get shopping done, in Plaka for instance, done in the afternoon? Thanks so much!
When they close, it's only part of the afternoon, roughly between 2 and 5 p.m.
In tourist areas, gifts and souvenir shops remain open most of the time, as do supermarkets.
For other stores just wait for the opening time and do something else.
I'm surprised to see Hydra in your list besides Paros and Santorini. Hydra is a destination to see mainly when you don't have time to go to other islands (like a sample of Cyclades style for tourists in a hurry)
And if you go to Hydra you will have to come back to Piraeus to go these other islands.
RS likes Hydra but for reasons unknown totally avoids any of the more fascinating Greek islands such as Santorini, Crete, Rhodes, Mykonos, Delos, Paros, Naxos, Corfu, Zakynthos, etc.
I agree a pass to Hydra. It was fine but uses up the time you need for a very busy two weeks schedule. I would chose Naxos over Hydra hands down but I think the travel time alone in your schedule is quite a bit. To answer your question in Naoussa, Paros, the nicer stores closed for a long lunch. Hydra had mostly touristy stores in general but I did find one cute toy store. Nafplio did have some longer lunch closers.
The more important thing that you might want to focus on is the island sequence. Every ferry hop uses up a minimum of a half day.