Wedding overseas

Hi I'm helping to plan my sister's wedding. She's looking to get married overseas in an all inclusive hotel with approx 20 guests. She is considering Italy (not Lake Garda), Greek islands or somewhere beautiful, she's not sure!! The hotel for guests needs to be affordable as they will be all staying for the week. Have you got any recommendations of where you have been or stayed that sounds like this? What sort of price are we looking at?
Thanks in advance x