A strong theme gives a staff party structure, atmosphere and a shared code. The most popular themes: eras such as the 70s, 80s or 90s. Nostalgia always works and the music and clothing choices are easy. Luxury and glamour such as casino royale, Las Vegas or an Oscar gala instantly give an evening allure.
Nature and adventure such as jungle or safari work well in large spaces. Colour themes such as white party or neon are easy to communicate with big visual effect. And a company-specific theme is the most personal, but requires creative development. The more consistently the theme runs through décor, music and catering, the stronger the atmosphere.