Hi Jan
I've been on holiday to Rhodes too though it was about 20 years ago and I suspect it's changed somewhat since then. Did you get to do the day trip to Symi, which is a beautiful little island? Do you have any male Cruises in your line? DNA testing might be able to provide the breakthrough if you are struggling with the paper trail. You can read more about my project here and how it all works:
http://www.familytreedna.com/public/CruwysDNAIf you are interested, my one-name study, is also featured in the current (June) issue of Family History Monthly in an article on the Guild of One-Name Studies. I'm mainly focusing on the names Cruse and Cruwys but I've also acquired a fair amount of information on Cruises in the process as the surnames are never stable.
Debbie Kennett