I would say as long as it is ok with her that there is not a surprise, then there is nothing wrong with it. :)

Last christmas my sister was really stuck as to what to buy her boys for christmas so her and her husband took the kids to the toy section and watched them as they walked around looking at all the toys. Just from watching them she got an idea as to what they wanted. Her husband then took the kids to buy an ice cream and my sister bought the presents.

Maybe you could try this, but i  think  it is ok for a 9 year old to know what she is getting.

 We have used "Wish Lists" in our house for a long time with our three kids. (They're now 23, 20 and almost-13.) Even my husband and I are asked for lists before our birthdays and for Christmas. We have emphasized, though, that these are WISH lists, and not order forms. So we take ideas from the lists, but we always try to get one or two things that are not on the list. I think that really helps show that we're thinking about them, not just about picking something from a list. Hope this helps.

I don't think it matters. It would be nice to get what you want at any age.

Have you thought of getting her to make a wish list?  That way, she gives you several ideas and you pick one, which would then mean it is still a surprise.

Failing that, you could always get gift vouchers and take her shopping.  I'm sure she would love this, especially if she were to pay for her purchases herself.  Big responsiblitly for.

.....im not sure if this really matters but  do know if i was nine and was asked 'what would you like???'.... gosh would be over the moon!!!