So, let's go through the list!
I just really dig the dynamics you can have with these pairings, and I'm especially interested in post-Iraq Ray, who is noted by Wright to be a much quieter guy. Like, who is Ray off Ripped Fuel and down from the war-high? How much of who he is on the page/screen actually carries over into his non-military life? And what's it like for Nate or Walt to respond to that? Do they find it hard to change gears, sometimes, or is the changing nature of Ray something they love about him because he's just RAY?
Ray (you're probably seeing a theme here)
Fuckin' loves me a character study, and I love all of these guys, so if you're in the mood to explore who they are and how they work and how they feel about themselves and what they do, I'd love to read it. Any sort of day-in-the-life shit would be grand. You can do them as the main character in an ensemble piece or maybe just them doing their thing. I am not picky at all. Some ideas to help you get your mind working: We know what Sixta's like to the men, but how's he seen by the higher ups? Who is he, really, when the uniform is off? Godfather's thoughts on his men when they stand outside his tent with that little boy; Godfather's thoughts on being in charge of these hardened combat men when he's mostly worked parade duty shit. How does Stafford see himself? His relationship with Christenson? His view of the world in general?
I am good with any stories based at any times. So, before, during, or after canon is great and diverging off canon is great.
Any sort of crossover/fusion you want to do with SPN would be killer. If you wanted to interrupt our known canon so Brad and Ray or Stafford and Christenson or maybe even Godfather and Sixta can gank a baddie local to Iraq, that would be pretty boss. If you just want to take our boys and drop them into SPN as a whole, go for it. It'd be great.
Just a few things I dig that might help you decide where to go with the story.
Actually, this list is stuff I'm NOT into, as the stuff I'm into is much longer. So, if you decide to go all hot-sweaty-dudes for me, please DO NOT write any sort of sexual humiliation, dub-con, watersports, extreme pain play, or any sort of unhealthy relationship in general. Everything else is pretty much free game. I am especially fond of spanking, quickies, slow burns, and bickery, teasing banter.
I dig crossovers/fusions as a whole, and maybe you don't know SPN or have no interest in writing it. Other fandoms I like that you might know or want to work with: Pacific Rim, Person of Interest, West Wing (+5 if you can get Lord John Marbury to pop up), Avengers (movie or comics), Iron Man (movies or comics), Captain America (movies or comics; oh, look, another theme).
I hope this letter has helped you get a few ideas about what you might write. I'm sure whatever you come up with is gonna be great!