I always avoid synergy and say "bigger than the sum of its parts" or "peanut butter and jelly". Simple language with less baggage.

...except for those of us who think that PB&J is a culinary abomination in which case the metaphor disintegrates ;-D (apologies to my mother for having to make me PB-only sandwiches growing up)

I do wonder whether adding chips or bacon to counteract the cloying one-dimensional sweetness of the other ingredients would make me a fan though... chunky natural PB, blackberry jelly, hickory-smoked bacon on ciabatta? Hipster PbB&J might be the ticket.