What: Monster Bash on the USS Hornet Museum
Where: Alameda, CA
Description: The ship’s annual Halloween party takes place onboard the historic aircraft carrier with costume contests, dancing, and haunted happenings.  The family event features 60s, 70s, and 80s dance music by The Cocktail Monkeys.  
When: October 31 from 8 pm to 12 pm

What: Happy Hauntings: A Kingdom for Kids! at the Dutch Wonderland Family Entertainment Complex
Where: Lancaster, PA
Description: Dutch Wonderland hosts non-scary Halloween activities including themed rides and attractions, trick-or-treating throughout the park, magic shows, ghoulish games, storytelling by the Princess and Knight of Dutch Wonderland, and more.  
When: On weekends in October from 3 pm  to 9 pm

What: Halloween Sleepover at the Pacific Science Center
Where: Seattle, WA
Description: Costumes are encouraged for the science center’s annual Halloween Sleepover, during which kids can enjoy treats and games and explore eerie science marvels, including spider webs and the amazing power of a full moon.  
When: From 7 pm on October 30 to 9 am on October 31

What: No-Scare Children’s Trail at Peterson Park
Where: Chicago, IL
Description: A spell has been cast over Peterson Park, transforming it into a No-Scare Children’s Trail, designed with little ones in mind. Enjoy a live, creepy critter show, a wacky hat art project station, treats, and instruction for learning the Thriller dance are on the schedule.  Costumes are encouraged.
When: October 24, 10 am to 1 pm

What: Old Town haunt
Where: Pasadena, CA
Description:  Housed in the basement of the century-old Union Savings Bank in Old Town Pasadena, this haunted house winds through the catacombs and vaults of the bank. The evening version is pretty darn scary; a less-frightening children’s matinee is available.
When: October 9 to October 25 – Thursday, Friday, Saturday and Sunday from 7 pm to 12 am; Matinee available October 17, 24, 25 and 31 from 12 pm to 4 pm

What: Monster Splash Nighttime Bash at Miami Seaquarium
Where: Miami, FL
Description: Families can find thrills and chills amongst the sea creatures at the Seaqarium’s annual Halloween celebration, including haunted houses for all ages, Halloween-themed animal shows, trick-or-treat stations, rides and slides, and live entertainment.
When: October 28 to October 31

What: Halloween on the High Seas
Where: Nashville, TN
Description: Set sail for a seafaring adventure as the orchestra encounters pirates, stormy weather, and hungry sharks lurking beneath the ocean waves. Music from Pirates of the Caribbean and other nautical favorites are on the play list, and student dancers from the School of Nashville Ballet perform as well.
When: October 31 at 11 am

What: Scream on the Green: Harry Potter at Centennial Olympic Park
Where: Atlanta, GA
Description: Centennial Olympic Park hosts a Halloween celebration with trick-or-treating, costume contests, and an outdoor screening of Harry Potter and the Sorcerer’s Stone.
When: October 31

What: Feast with the Witches at The Children’s Museum of Indianapolis
Where: Indianapolis, IN
Description: Enjoy a breakfast, lunch, or dinner “boo-ffet” with the witches, Halloween entertainment by Ruditoonz in Lilly Theater, and a ticket to enter the Tomb of Doom Haunted House.
When: October 20 to October 27

What: The Not-So-Scary Haunted House at The Magic House
Where: St. Louis, MO
Description: More than one dozen costumed storybook characters like Peter Pan, Harry Potter, and Cinderella mingle with young visitors, who can come in their own costumes for trick-or-treating throughout The Magic House and receive an autograph book to collect signatures from the “celebrities.” Older children are invited to take a spooky walk along the Haunted Trail.
When: October 23 to November 1

thanks to parentsconnect for this info