Circling back to this. A couple points:
-Don't go to Guam just because you want to "do SAR". Yes they do stand SAR Alert and get more rescues. However, it's an island in the pacific (good and bad, but isolating), their deployments are different, and you're (for better or worse) far away from the motherships of North Island and Norfolk. I knew a lot of people who went there and couldn't wait to leave.
-Norfolk, North Island, and Japan are actually all good places.
-You'll learn more in the fleet, but last I heard (and it'll change again I'm sure), you have to "self select" out of production jobs like FRS/VT/HT before you could apply for Station SAR. This is a risk and you could end up at a desk. I'll say VT IP was some of the most fun flying I did and really rewarding, plus you get to manifest being the instructor you wanted to fly with. I still keep in touch with a handful of my on wings and offer them the occasional career advice.
-I launched on SARs off the boat, but never got a save. I don't consider my helo career less than because of it.
-As others have mentioned, Coast Guard DCA is a tightrope walk with a lot of "maybes" and you've got 8 years of MSR to run out before then. Total YOS might be an issue you can't get a waiver for. Things can absolutely change between now and then with regards to manning, but at the moment PERS won't let you go a day earlier than they have to, and they're using every tool in the box to send and keep people on the boat.
-Copy and paste the above for ANG/AF Reserve. My neighbor (former HSM, VT IP, now 121 pilot and VT Reservist) has been "accepted" to the local KC-135 unit for 9 months now and still waiting for paperwork from AF HQ. Likely not a primary plan unfortunately, unless you find a gig in the meantime.
-With 121 hiring, HEMS and LE helicopter flying is opening up more, might be worth considering
-No idea what things will look like in 8-10 years when you get close to 20, but settling down somewhere you choose and flying turns to the Caribbean for spring break or Europe might sound nice. Endless moves and deployments take their toll, even if there's fun mixed in.
Regardless of all of the above, enjoy your first sea tour wherever you end up. There's literally nothing like it.