Will be traveling to Greece in September... have already decided on 4 nights at Blue Palace, 4 nights at Mystique, and 4 nights at Grand Bretagne... would like to add one more stop and am deciding between The Romanos Costa Navarino and Santa Marina in Mykonos- where would you choose? This will all be on paid stays, so no need to factor in redemption differences if there are any. Is 4 nights in each locale a good amount of time? Many thanks.