For a wedding in Sardinia this has also become a great opportunity to gather all friends together, especially if they are living abroad and have few chances to meet.
Usually the rehearsal dinner is more informal than the wedding reception and can be a casual outdoor BBQ, a buffet dinner on the beach or a dinner in a local pizzeria. The food and atmosphere should reflect or complement that, but it mainly depends on how many guests will be there, and what kind of party the host has in mind.