If you decide on a Med cruise, realize that, if you plan on enjoying all there is to offer in the wonderful Med ports, your days will be like 8-10 hours long for excursions. I think I only had 2 sea days, on my Med cruise on the Magic, last spring, and wouldn't a sea day most likely be your choice for the wedding? This is where the onboard wedding coordinator will be your best friend, figuring out the logistics for your group, onboard.
Another thing to remember is, June/July is in the midddle of high season, and, ports will be very crowded. Does the couple want a leisurely, or a busy busy honeymoon? Have they considered a Caribbean option? I know there are less ships there at the time, so, your choice of ships is considerably less,& as Donna mentioned, Princess, and, RCI are the ships doing weddings.
Your relationship with a cruise specialist in this instance, is cruicial, to make this joyous occasion the best it can be. Do not book through the cruise line. You should also get a free berth with 8 cabins. Also make sure the group buys travel insurance, in case of any kind of emegency.The TA can fill you in all all your options. Good luck,and klet us know how you make out.