I arranged a birthday party for my niece and about twenty of her friends at the Exploratorium in San Francisco. The Exploratorium mostly does parties and events for children of various ages, though they also have occasional adult-oriented events. The Exploratorium is really popular with many kids my niece's age (6-10), and she and her friends had a good time exploring the museum and playing with magnetic sand, giant bubble curtains, and other exhibits. They also enjoyed the activity part of the party - we did the Flight party, where the kids made model helicopters and airplanes. I really enjoy the tactile dome, which is an optional party extra, but it's not for people who are afraid of close spaces or the dark, so we skipped it on our trip. The Exploratorium employees were all very helpful and interested, from the folks who dealt with the event planning to the person who ran the activity part of the party to the random volunteers who answered questions throughout the museum. A party at the Exploratorium is a good hands-on science experience for kids: it's casual and entertaining and educational. The arrangements were sometimes difficult; the museum doesn't have staff who can pick up deliveries or help move food, for example, so one of the adults had to stay in the front reception area to wait for the food and drinks to come in. The timing was a little awkward, too, because they don't have that many spaces and they have set times that parties are awkward. I would recommend the Exploratorium for kids' parties, especially if you have the time to take care of the arrangements yourself. If you're less interested in doing the set-up, I've also organized activity parties at the Lawrence Hall of Science, where they can cater your party and make treats and grab bags.