Definately Navy or Air Force. However, even these two services are sending people to Iraq and Afghantistan. I've been in the Navy for 16 years now, and made 6 deployments to the Persian Gulf; one of those was in country guarding detainees for a full year. Working right along with us were Army National Guard MP Companies and Air Force Security Squadrons. Our Navy unit was a 400+ Battalion.
However the desision is ultimately up to her. The Air Force has a much better quality of life than the Navy, however, the Navy get more travel than any of the other services.