Well then, I'll step up and give the run down for CGA.
Obviously the first summer is Swab Summer, seven weeks long including a week on CGC EAGLE, the Dirty Bird.
For your Third Class summer you'll have around 5 weeks aboard EAGLE and five week at an operational Coast Guard cutter (cutter is what you call a Coast Guard ship). Some will go to EAGLE and summer school if need be. I've also heard that now some will go to Sectors...
For your Second Class summer you have a few options, or atleast you did when I was a 2/c cadet. You can be Swab Summer cadre (first and second make), NAPS Cadre, EAGLE Cadre, or AIM/MITE (no more MITE I think) Cadre. In addition to that, you will have LAMS (leadership courses), ROTR training (why I schooled USNA69 on ROTR), CATP (Cadet Aviation Training Program), and leave. Before any of this happens, and before graduation, the TRACEN Cape May Company Commanders arrive in New London to teach you how to train. They are very good at what they do, and they are very professional. If you can approach the level of training they give, you're doing a good job. CATP is great; when I went it was at ATC Mobile. Keep in mind this stuff have changed over the past 5 years, so it may be very different.
For your First Class summer you have the option of spending 10 weeks at a unit, or 5 weeks at two different units. These vary quiet a bit. You may spend 10 weeks on a cutter, 5 weeks on a cutter and 5 weeks at an internship (where? who knows, the sky is the limit), 5 weeks Sector and 5 weeks cutter, 5 weeks Navy Dive School and 5 weeks cutter, 10 weeks at Batt. Staff. It's hard to cover that 1/c summer because there are so many possibilities.
What I do know, if you go to a cutter for the summer you will be doing that mission. As a 3/c, I was assigned to a cutter that was patroling in the Florida Straits and elsewhere. We were engaged in migrant interdiction and found boat loads of Haitians, and a few Cubans that summer.
You will get yours hands dirty, whether your doing fisheries in the North Pacific or North Atlantic, migrant and drug ops in the Florida Straits or off of the west coast. You will be a guest, and you have to remember that, sometimes you may not like the unit you're at, but the next unit you may fall in love with, this happens in the regular Coast Guard too, and it can even change while you're at the same unit, as a bad apple or two ship out or report aboard. Keep an open mind. Swab Summer and 2/c summer are dedicated to training, while 3/c and 1/c summers are for operational experiences.