I also second Chile. The terrain and geography is varied. Desert, beach, Patagonia, nice smaller cities like valparaiso. And Santiago is one of my favorite cities.
It is very affordable and very safe.
From my own experience as a man in morocco I would not go there as a single western woman. It is just too much to handle.
I know people will say it is perfectly safe. And it can be. It can also feel very intimidating and unsafe especially if you are on your own. And it isn't warm in December.
Chile is very warm in December. I would splurge and go to Easter island which is simply stunning.