I'd recommend seeing if you can find flash of some of the things you want online and maybe have your guy piece the sleeves together. Good WWII fighters can sometimes be found in traditional American flash (sailor jerry, don hardy, etc.). It depends on which styles you want your pieces to be in. Realism, traditional, etc can be very different but mixing styles can be cool. It may be worth while to have more than one artist add to your sleeves.
However, I've always found that the more freedom I give my tattoo artists, the better the end result. Good tattoos happen when the artist is just as stoked as you about the pieces they're doing on you. Most of the time, I just ask for traditional American style, give the artist a subject like pin up girl or whatever and let them go nuts. Last time I got tattooed my artist had my piece already sized and ready when I got to the shop cuz she was so stoked about the design she'd come up with.
I hope you get an excellent tattoo!
Mr. Ink, I also hope you return... <S>