Some free-associated sounds that I would tag for the holidays...
- excited children in the living room
- sharpening a carving knife
- cash registers
- busy crowds
- tire bys on slushy streets
- cold blustery winds
- fireplace crackles
- scissors shearing wrapping paper
- glasses clinking in toast
- intimate groups of celebratory tone
- large office parties with a little too much booze and honesty (that one's a little cliché, but still funny)
It's probably obvious that I come from a Xmas-celebrating home in a colder climate. Like Ryan said, knowing what you're selling or how you're selling it would help focus ideas.
EDIT: @Dave's salvation army ringer reminded me of the handbell choir I used to play in, we'd go around to people's parties or homes and perform carols. Pretty Xmassy, but another sound that triggers "holiday" for me.