We used to mail postcards every time we went. It took about 2 months to get them. So we would just jot down the highlights from vacation and then when we got the cards 2 months later, it would trigger a bunch of little things about the trip we had forgotten in that time.
And for the person that asked, yes, it you want GS to mail them for you, it would be a Bahamian stamp, not a US one. But you can get those from GS so it isn't a big deal.
(If the post office is open, you need cash - US is fine -- but bring smaller bills. We have often gone in and they didn't have change. I have 6 or 8 stamps I pre-purchased for our next trip because they didn't have change, now I can't find where I put them!!)