What a precious panel. Yes, Spoonflower.com does wonderful work & IMHO isn't that expensive for something we can't do by ourselves. I used them for a crossword puzzle and clues on my MIL's 90th BDay quilt here:
https://www.quiltingboard.com/pictur...h-t155965.html
Unfortunately I don't have any quilting suggestions but want to say how beautiful your DGD is and what a lovely memento this will make for her. I hope you will post your finished wall hanging for us to see.

Yes, please post a pic of your finished quilt. I would love to see it.

No idea on the quilting but that is going to be a fantastic wallhanging.

That is amazing!!! I’ll be no help on quilting...but it’s going to be wonderful, I”m sure!! I’m glad to know about this site!! Thank you!! And good luck!!

What a beautiful young girl! Omg those pictures are stunning!!
Sorry I don't have quilting advice though........ :)