I would get a book at the library showing Hawaiian quilts, pick out 4 or 5 I would enjoy working on, photocopy them and send them to her to see if she likes them. My friend brought me a kit for a pillow when she traveled to Hawaii and it had one piece that had been cut when it was folded in 4s. ( Like when we use to cut out a snowflake from paper.) It was breadfruit which is their local product and attractive. Ask her to send a sample of a fabric or two that she likes for the main large Hawaiian center so you are on the same wave length, or do the main large Hawaiian center in blue with pretty quilting in white. It would be sad to do a beautiful quilt and if it does not appeal to her it will not be loved. Maybe she could send photocopies if quilts she likes.I think Hawaiian quilts are done in only 2 colors and usually both are solids??? I am not certain on this and rules are meant to be changed. You are very nice to make her a quilt.

Hawaiian quilts are a (a style) of quilt---
perhaps you should do a search and look at 'hawaiian quilting' before deciding- since a turning 20 or any others you mentioned are very much- not hawaiian quilting.

hawaiian quilts are appliqued--and very beautiful...the fabric she chose would be beautiful for the appliques- with a white background.