Doug Winterburn provides:
http://usmilitary.about.com/b/a/067605.htm

Air Force reenlistment rates are always significantly higher than those for the
Army. There are a variety of reasons for that, including more technical
training, no need for grunts, less need for front line discipline, and on.
Oddly enough, Marine Corps rates are also higher, usually significantly.

I'm not sure reenlistment rates reflect satisfaction within the military as to
their mission as much as they reflect the economy at a particular period, along
with visible opportunities to advance within any of the services...added to
pride of service. Reenlistment bonuses help, too, though not as much as the
military might like.

Oddly enough, the Air Force and Navy are both planning reductions in personnel
numbers next year--I seem to recall the Air Force getting ready to drop 5600
people from their overall roles. The Army is looking to, as they say, turn
"Blue To Green". They want anyone over E5 who is released in the program.

For a general look at military matters, try military.com.

Charlie Self
"When you appeal to force, there's one thing you must never do - lose." Dwight
D. Eisenhower