Did you read these threads?
first greece trip ... Amanzoe and ??
Santorini: consolidated thread (combined 1/17)
I've been to Elounda twice and stayed at the Blue Palace and Domes of Elounda. For me Domes was significantly better than the Blue Palace.
As for the other islands, my research has turned up the following which seem to be the best options (but are not always "luxury" options):
Paros - Calme Boutique Hotel
Naxos - Naxian on the Beach and Villa Marandi
Ios - Liostasi Hotel & Suites, Dionysos Seaside Resort and Ios Palace