I am 66 and I love your quilt. If those are the colors she likes, I would just finish it up and give it to her. You said you wanted something more sophisticated, but there are a lot of us "sixties" folks who don't think of ourselves as sophisticated. I wouldn't know what to do with a sophisticated quilt, but I sure would use yours.
Your quilt is not childish, it is cheerful.
Dina