@branko, I think you and Pitchfork are right, and we should drop the idea of giving it directly to Jessica. I still think we should emphasize YA titles, though.
Regarding Baen books, when I was that age, I really enjoyed the works of James H. Schmitz. The
Telzey stories are available through the Baen Free Library;
The Witches of Karres is available as an eBook for $5. I'm open to other suggestions. I do try to be careful of what I suggest for kids not my own -- I'd let my kids read Niven, for example, despite occasional "mature" content, but I wouldn't assume someone else would. Baen offers
this list of suggested YA titles. I am not, myself, much of a "military sf" fan, but I see
Lord Darcy in the list, and a few books by Andre Norton. Any other suggestions?