I haven't been to the Iberostar in Jamaice, but I have been to the ones in Riviera Maya Mexico- and they are beautiful. I am sure it will be perfect for you.
Welcome! We just decided on our resort last week- we are getting married at the Dreams Riviera Cancun next year- this site will become addictive, there is tons of info!
Greece will be an amazing place for wedding-- as for save the dates setting up a website with RSVP's is a good idea (mentioned earlier). Our initial numbers are coming just from conversations we have had with people, or emails.
Good Luck!