Better get more details from the kids!!
I would also give them parameters of what you are willing to do -
Size limit (Do you want to do a 'to the floor king-size bedspread'?)
Give them several designs to look at that you are willing to work on - they would not necessarily be limited to those, but you might get an idea of what they like (or don't like)
Color schemes - black and white, pastels and white, 30 feedsack repros, civil war, floral -
Or even select pictures of quilts from the picture section here and forward them to the kids to see what they like?
The "Vintage but not old fashioned" description has brought out all sorts of ideas from the members here of what it might be - - -
My reason for suggesting limits: I offered to make my DIL a quilt - and what I had in mind was couch size (about 60 x 80) and what she wanted was a king-size. I wasn't planning on covering a football field!