Books. You can't have too many books. (Don't double-check that with my husband, please.)
Art supplies. Not kits! Just paper, watercolors, clay, drawing pencils, pastels, tempera paints, etc., in a nice basket, for her to make discoveries with.
A trip to the nature museum, art museum, history museum, zoo, whatever is near you that your daughter would like. Include a special lunch.
A day with the grandparents all by herself.
If you have such a thing where you live, an afternoon visit to a very fancy tea shop for high tea.
On the other hand, does she love horses? Is there a stable where she can do some riding?
I'm about to talk about a toy now, but bear with me. One of our granddaughters once asked for a "good" dollhouse. By that she meant NOT a plastic thing that would fall apart in a week. A lot of us relatives got together and gave her a very, very nice (also costly) one, complete with dollhouse family, and continued to give her rooms of furniture on subsequent birthdays and Christmases. She still loves it and, she says, wants to keep it forever. Maybe she'll be able to pass it on to her daughters one day.