选择晚会背景音乐的开场音乐时，通常要考虑以下几个因素：节奏感、欢快的旋律、轻松愉快的氛围。以下是一些适合作为的推荐：

1. "Celebration" - Kool & The Gang

2. "Happy" - Pharrell Williams

3. "Don't Stop 'Til You Get Enough" - Michael Jackson

4. "Walking on Sunshine" - Katrina and The Waves

5. "I Gotta Feeling" - The Black Eyed Peas

6. "Uptown Funk" - Mark Ronson ft. Bruno Mars

7. "Can't Stop the Feeling!" - Justin Timberlake

8. "Dancing Queen" - ABBA

9. "We Are Family" - Sister Sledge

10. "Good Vibrations" - The Beach Boys

这些歌曲都具有积极向上的节奏和旋律，适合为晚会热身并营造欢快的气氛。请根据自己的喜好或晚会的主题进行选择。