I'm intersted in making this for the moms at my daughter's birthday party this weekend. I'm not familiar with elderflower. What is it like?

Floral but not in an overly perfumed way would be my description.

I think it's similar to cassis in flavor, but a bit more floral. I've tried both the St. Germain and one made by Thatcher's, and prefer the St. Germain. Ikea also makes an elderflower syrup that is good.

I only know it from the liquor St. Germain, which is an elderflower liquor. It's floral and sweet, nice for mixing especially with bubbly! http://www.stgermain.fr/