I lived in Grenada for a couple of years. It's a chill, safe place. I had my family there and we always felt safe, as long as we kept an eye out for speeding buses when crossing the street. It certainly checks the boxes you specified. Night life is limited. I'm planning to go back for a vacation in February.

As I recall there is a time of year that gets very windy. I think that's in winter, but my memory is fuzzy. The internet says February is the windiest, and that matches some of my memories. In any case it's always warm. I wouldn't worry about rain. That's tapered off by December. If it does rain it's a warm rain, and it's likely to come in short showers so I don't think you'd be stuck inside all day.

If you want to be in walking distance to amenities I'd recommend staying near Grand Anse. You can also get public buses there. (They are actually vans.) There are resorts close to the airport, but in those places you'd be dependent on taxis to get away from the resort - which might be fine if you want to be somewhere quieter.