Cody has it right. I would go with 6 months, if left up to me.
Soldiers simply need to fall in on pre-positioned equipment. There is no value in keeping them there for 15 months....even 12 months for that matter.
There's so much Iraq experience in this Army that any newbies will have instant experienced leadership to bring them up to speed.
I don't think we have the numbers to deploy with that kind of turn-around. In order to accomplish that, we'd have to drastically increase the size of our military either through recruitment or a draft.
My husband has been there and is actually looking forward to the 15 month rotation. He said that there's a window where the out-going people overlap with the in-coming people to show them the ropes. You have several months where people are settling in and getting comfortable with the situation. He said that after the 9 month mark, people get comfortable and really start to shine at their jobs. At the 10-11 month mark, the new folks are coming in, "your head" gets screwed up with thoughts of going home and it's over.
With the 15 month rotation, you have a solid 6 months of everyone doing their jobs with confidence and a good routine.
Of course, he also thinks that we should go back to the way they did it during WWII when everyone went for the duration of the war, so you can take it with a grain of salt. (He's old-school.)
As the wife, I don't *like* the longer deployments and I'd *love* to see 9 month tours, but I'll support the situation no matter what they do.
I can stand on my head for 6 months.