Three types of skewers: red meat, poultry, fish.
Considering it's a wedding, you're best red meat option is probably tenderloin. You'll want about 30 pounds trimmed. Have your butcher do the trimming, your plan is already pretty darn ambitious for your own wedding.
I suggest marinating the meat briefly in a 50/50 mix of red wine and worcestershire, then sprinkling them with seasoning just before grilling. The seasoning mix should be kosher salt, black pepper, smoked paprkia, granluated garlic, granluated onion and a bit of thyme and sage.
Poultry -- well chicken. What else is new? Thighs are easier and surer than breasts. However breasts can be done if they're brined, rather than marinated. Your best option might be marinating thighs (cut them in quarters) in olive oil, lemon juice, onions and garlic, seasoning them with the same seasoning used for the beef; then sprinkling with dried oregano and lemon juice just as they come off the grill.
You'll want 25 pounds skinned, boned and cubed. If you want me to calculate waste for you, I'll be happy to do it. But again, ask your butcher.
For the fish skewer, either salmon wrapped in (really good) bacon; shrimp brined in water, satl, chili, limeade, and tequila; or, if you really want to splurge, you could do lobster tail instead of shrimp. You want about 20 pounds of shrimp, lobster or salmon. If you decide on shrimp, no matter what else you do, have them cleaned.
Set each table with three sauces -- remoulade, spicy ketchup and a mild salsa verde.
Lots of different salads and an array of warm dishes, too. If it were my party I'd go Mediterranean with rice pilaf, tzatziki, tabouleh, babaganoush, dolmas, spanakopita, Greek salad, pickled radish, Greek flat bread (not pita, pita's too dry), and whatever.
There are innumerable options for side dishes, whether themed or not. I don't expect you to consider my suggestions as sent down from on high, carved on stone tables. Rather, they're just ideas to get your creative (and gastric) juices going.
Oh. And very best wishes,