The Astir Palace used to consist of the Westin, the Luxury Collection Hotel Arion and Bungalows. While today it operates as one hotel, there are still the 2 buildings Nafsika and Arion as well as the bungalows. The atmosphere is also relatively different, I described that in my report at the time. Hence the (accurate) statement that it is actually 3 hotels in one.
Whether the surcharge is worth it depends mainly on the location. I am honestly amazed at the prices mentioned by A4K, that is much cheaper than what I have seen last. Normally I would say for only $183 more I wouldn't think twice and go to the Astir. But you have to know that the FS is just not in town, but outside. You have to drive into town first.

Amanzoe is a hotel of the chain Aman on the Peloponnese and from the hardware with the best I have experienced so far in Europe.