Immersion

[zuma022]

I'm thinking about going to a Spanish speaking country for a couple of weeks in May and was wondering if I could get any input.
My first choice was Bogota or Medellin, but it looks like May is right in the middle of the rainy season. I have been to Quito, so I assume the climate in Bogota would be similar, so even in the rainy season it's not full on rain and in summer it's not actually very warm. Has anyone been or would you go in May?

Lima is another option, but I worry that it is too overrun with tourists to get much of an immersion experience. Same goes for Guatemala which is also an option, but I heard Antigua has the restaurant menus in English even. I'm sure both countries have areas that are less touristy though, but I don't really know enough about it. I think it's a fine balance between tourism and safety.
Mexico City is another one I'm thinking about, but to be honest I have no idea about the safety there. I would assume it's no worse than many US cities, but all the news out of Mexico are rather bleak.

I'm looking for a city that is safe for a single female, that has a somewhat neutral accent, is not too touristy and not too far from Western Canada. I think that I would book some private classes at a school and also do a homestay through them. I'd love to visit Buenos Aires or Montevideo, but I think it's too far for barely 2 weeks.

Does anyone have any recommendations or input?