Great idea to only give presents to the kids, although....isn't that what Santa/Father Christmas is supposed to do? Growing up in The Netherlands, I only got presents from St. Nicholas on December 5th....presents from my parents; not from grand-parents, so why do we even give our grandkids presents for Christmas? Isn't that what birthdays are for?
When my kids were small, they only got presents from Santa (paid for by us parents) on Christmas Day, and on the four Advent Sundays leading up to it, they would get a small gift from us as the parents.
Now that we have grandkids, I have given them gifts for Christmas, but they do not need them, with all the many they get from Santa, and from their parents, and grand-parents! In my grandson's case, he gets presents from the grand-parents, plus now also his step-grandparents!
This year, I have one gift for each of the grandkids for Christmas Eve; second hand!!! I actually have given them secondhand Playmobil toys bought on Ebay last year. They do not care
As for wrapping....you could consider making a cloth gift bag that can be reused every year. You could even tie a pillow case with the gift (s) in it.