Vow Renewal take place on the yacht quite a bit. The price is 350 for up to 12. (extra for catering) If you are having 20, then I would suggest someplace like the beach near the polynesian with the Castle in the background. Here are a few ideas. I don't know if they will help, but the information of what is available can't hurt.
Good Luck,
Pam
If you are having 20 people, you can do something like the Magical Gatherings and take advantage of some of the special things they have to offer like dinner at one of these restaurants;
Disney's Spirit of Aloha Dinner Show
Dancers head up the cast of this all-your-group-cares to eat dinner show at Disney's Polynesian Resort.
Hoop-Dee-Doo Musical Revue
Disney's Fort Wilderness Campground presents hilarious vaudeville-style entertainment at Pioneer Hall, plus all-you-can-eat vittles.
Whispering Canyon Cafe
Barbecue favorites served to large groups in rip-roarin' style at Disney's Wilderness Lodge.
'Ohana
Treat your group to skewers of shrimp, poultry, pork and beef served straight from an open fire pit at Disney's Polynesian Resort.
Yacht Club Galley
Enjoy a relaxed meal in this New England-themed restaurant at Disney's Yacht Club.
Cape May Cafe
Step up to the buffet for a New England style clambake at Disney's Yacht Club.
Shutters
Old Port Royale's bustling Market Street is the perfect backdrop for casual dining at Disney's Caribbean Beach Resort.
Trail's End
All you and your party care to eat home-style, frontier buffet at Disney's Fort Wilderness.
Prime Time Cafe
Eat in the kitchen of your favorite 50s and 60s sitcom family while watching TV clips at the Disney-MGM Studios.
Mama Melrose
This charming Italian eatery is the perfect spot with brick-oven pizza, fabulous pasta and more at the Disney-MGM Studios.
Restaurant Akershus
Dine at Epcot® in a replica of a medieval castle and sample a bountiful buffet of Norwegian cuisine.
Biergarten
Enjoy a German banquet of food, fun and entertainment at Epcot®.
International Dinner and Illuminations Reception
Clients are directed to the Odyssey Restaurant, where they see the primary colors of international flags lined up side-by-side, symbolic of Epcot®'s theme of international friendship.
Inside, the sounds of music and the smell of fine international cuisine complete the perfect ambience for a dinner at World Showcase. This incredible experience offers delectable food from all over the world, from Asia to Italy, with dishes consisting of pasta, chicken, sausages and assorted vegetables, just to mention a few.
Following dinner, a surprise Disney character appears for a meet-and-greet with the children.
After the character experience, everyone is invited to follow their guides to Towers Plaza where they will enjoy dessert and VIP viewing of IllumiNations: Reflections of Earth.
The International Dinner experience is available Mondays and Fridays at Epcot®, at a cost of $59.99 for guests ages 10 and older, and $19.99 for guests ages 3-9.
Safari Celebration Dinner
Parties journey through the park's authentic African plains and across the sweeping, baobab-studded savanna, spotting giraffes, elephants and other wild African creatures with their own private guide.
Following this special safari, guests move to the Tusker House Restaurant where they meet their host who welcomes them to a delicious dinner consisting of chicken, vegetables, assorted Artesian breads and more.
During dinner, guests have the opportunity to get an up close animal experience with one of the Animal Programs Keepers, who arrive with a live animal and answer any questions that guests may have about the Kilimanjaro Safari or Disney's Animal Kingdom®.
As a special part of the celebration, the host introduces two very special residents of Disney's Animal Kingdom® who wanted to stop by, Terk and Timon! Guests have the opportunity to enjoy a meet-and-greet with these loveable Disney characters.
The Safari Celebration Dinner experience is available Sundays and Thursdays at Disney's Animal Kingdom®, at a cost of $59.99 for guests ages 10 and older, and $19.99 for guests ages 3-9.
Good Morning Gathering
During this experience, guests are escorted from the front gate of the Magic Kingdom® to Tony's Town Square Restaurant where they are welcomed by the restaurant's proprietor himself, Tony.
As they enter the restaurant, smells of a hot cooked breakfast fill the air. Once guests are seated, Tony welcomes them by singing with, of course, an Italian flair!
Pure hilarity ensues as Disney characters Chip, Dale, Donald Duck, Daisy Duck and more enter the dining area wearing comical outfits and carrying baskets of warm muffins, fresh out of the oven for the guests to enjoy.
The characters then disperse into the restaurant to meet-and-greet guests with music playing throughout the restaurant during breakfast, which consists of a wonderful assortment of pastries, scrambled eggs, bacon, sausage and much, much more!
As another special treat, Gatherings have an opportunity to spend one-on-one time with the big cheese himself, Mickey Mouse, for photos and more. Then it's off into the park with memories of this once-in-a-lifetime Grand Gathering!
The Good Morning Gathering experience is available Tuesdays and Saturdays at the Magic Kingdom® Park, at a cost of $24.99 for guests ages 10 and older, and $11.99 for guests ages 3-9.
Magical Fireworks Voyage
As guests arrive for this Grand Gatherings Experience, they will enjoy an outdoor dessert reception. Captain Hook and his fumbling first-mate, Mr. Smee, will join everyone for a meet-and-greet on the pier before boarding the vessel for this exciting journey!
Playing host for the evening is an unforgettable comedic pirate named "Patch", who guides the guests through the unpredictable waters of the Seven Seas Lagoon, while leading them in sing-alongs and playing Disney trivia games.
After the fireworks show has ended, the ship heads back to the pier while Patch narrates the exciting story of Peter Pan, who just happens to be awaiting the boat's return to dock, ready to pose for photos and sign autographs.
The Magical Fireworks Voyage experience is available seasonally on Mondays and Saturdays on the Seven Seas Lagoon near the Magic Kingdom®, at a cost of $29.99 for guests ages 10 and older, and $14.99 for guests ages 3-9.