My daughter is travelling through Central America and spent a couple of weeks in Antigua, Guatemala studying Spanish ( the city is noted for it's Spanish schools) in November. She described Antigua as a lovely colonial town, found the people very friendly and hospitable and thought the place was very safe. There are tons of people there from all over the world taking Spanish courses and if you're with a group you won't have anything to worry about. She was was surprised that the temperature was cooler than she expected, so I would definitely bring along a sweater or light jacket. Now it might be warmer in March.
Perhaps someone else can comment on that.
Etta in Toronto