...Is it best to live in the cities or second tier areas?
Depends on what you want and how you will get about, and what you mean by "second tier".
For example, there are many places in the city proper that are "second tier" (and third, fourth, etc).
Living within a kilometer or so of Microcentro (Recoleta, Retiro [some parts only!], San Nicolas, Monserrat, Balvanera, parts of Palermo closer in) is pretty common amongst many expats. Recoleta and parts of Retiro are relatively expensive though bargains can be found. Others live in less expensive areas like San Telmo, Constitucion and others.
There are sort of surban areas in some parts of the city, though it's city suburban. Those places are pretty cool, but away from the "action" perhaps in many cases (my personal preference). They are also considerably cheaper per square meter. Belgrano has a particularly nice suburbanish area, and I know a Peruvian family who lives in Parque Patricios in a pretty nice place, twice as big as my apartment and almost half the cost! In fact, my lease is up for the last time in April (after 4 years of living in this apartment) and I'm thinking about Parque Patricios myself. That or a bigger apartment I found recently near Santa Fe and Coronel Diaz (near the corner of one part of Palermo) that is about the same price as I'm paying, but the owner where I'm living wanted to literally double my rent...
There are places just outside the city (I'm familiar with the north), Olivos, Vicente Lopez, Tigre, etc. Nice places, richer element, still accessible reasonably to things you would need to live on a daily basis without a car. Houses, apartments, a lot of upper and middle middle class and lower as well.
There are places further outside the city (again to the north I'm familiar with) like Tortuguitas, Garin, Pilar, Escobar. I used to live in Garin, closer to Tortuguitas, round 15 clicks from Pilar towards the city. There are a number of closed neighborhoods and country club neighborhoods out there, mixed in with bigger (and usually walled) middle class houses, and a lot of lower class housing, fewer decent roads and a near necessity to have a car to go to the supermarket, hardware store, etc., depending on exactly where you live.
Also, I know there is the latin temper thing that you'll find in mexico and other latin countries such as brazil. I have experienced it first hand. i know they have occasional tantrums but I am not sure how that is different from other latin countries.
any way will look into it.
I didn't mean to scare you off Porteña women, that was not my intention at all.
However, I grew up in Texas where a lot of my friend's parents, from Mexico, barely spoke English. My ex-partner and still good friend married into a Mexican family in Texas. I've worked over a couple of years in Brasil (months at a time) around Rio and a little north of there. I've had a few Brasilian girlfriends in those times. A good buddy of mine still lives in Bahia and is married to a Brasilera.
I've been married for 6 years to a Latina from Paraguay and know her myriad, gigantic family. A LOT of females.
I have a good idea of the Latina capacity for fire. And I love it.
Again, I don't want to spook you from Porteña women. I have met many good people here. I have known many Porteña women who don't come off hysterical to me. But there is a difference when you see Latin fire, and when you see Porteña/o hysterics. Maybe the guys I know simply can't get dates with decent women, for whatever reason.