Actually, we just recently got our youngest her own grown-up Bible. We opted for the KJV because it matches Daddy's.
However, we did have a hard time finding one that she could grow with and finally found one that we all like. There are so many out there! The one we chose is called "The King James Study Bible for Young Believers"/ Thomas Nelson Bibles (ages 8-12). There are no margin notes, the writing is a bit larger, Christ's words are in red, and it's burgundy like Daddy's.
We were a bit worried about (as Reba noted) the language being difficult, but decided that since Daddy's is KJV, as is our Pastor's, then she would better be able to follow with the same wording. So far, so good! But... there have been numerous times when we had to discuss what certain words mean! For us, it's fun!
Anyway, if this is too much information; please accept my apolgies!
The 'helps' in the back were the clincher:
http://www.thomasnelson.com/consumer/product_detail.asp?dept_id=310&sku=0718003756Giant Print KJV Bible Text
48 pages two-color inserts
Verse-by-verse setting
Words of Christ in red
My Decision Record
My Baptism Record
Unique KJV Word Index with illustrations
Dictionary/Concordance with illustrations
8 pages of full-color maps
8 pages of Secular & Biblical Historical Timeline