This may be a bit out of date; however, its definitely relevant. In terms of each years options for Marine training:
PLEBE SUMMER
Interestingly enough all Plebes attend Plebe Summer.
YOUNGSTER SUMMER
I've had friends who went to Jump SchoolDive School during this time. Otherwise its grey-hull time and maybe some CSNTS.
SECOND-CLASS SUMMER
Marine Corps TRAining for MIDshipmen (MCTRAMID)
-Not sure if this program still exists, but you used to be able to go to Quantico, Yuma, Pendleton, or Lejeune for two weeks of Marine exposure
PROfessional TRAining for MIDshipmen (PROTRAMID)
-While many other communities are also given exposure, the Marines get their crack at it too.
FIRSTIE SUMMER
Leatherneck
-Very important. Generally, must do either this or a MAGTF cruise with rare exception. Not wholly indicative of life as a Marine Officer. Gives a general overview of life at TBS. At the cyclic rate. Some classes have seen a dramatic downturn in the appeal of the Marine Corps after having attended this program. I personally believe this is because some people don't possess: 1) enough of a sense of humor, and/or 2) perspective (i.e. holding the longview of leading Marines).
Marine Air Ground Task Force (MAGTF) Cruise
-2/3 weeks experiencing the life of a company grade officer in the MAGTF. Experiences vary widely based on location, unit assigned, and officer assigned as a running-mate.
Plebe Detail/Cadre
-Seen as an important leadership step by the Marine Selection Board.
This is what I have observed. I also know of Midshipmen participating in CFT up at USMA. They were aggressively scouted by the Marines. Any hint of wanting to be in the mud will get their attention. I also have a friend (a recent grad of USMA) who commissioned as a 2ndLt (notice: not a 2LT). He is currently at TBS and got selected to be an Infantry Officer. So far as I know he is the only Marine officer from his class at USMA. I know of one other from the previous class year. Both of their father's were retired Marine Officers, and the did extensive work to get cross commissioned. Both actually attended Leatherneck as Secondclassmen. Its a rough road to travel.