Argentina is a large country, so your plans are decided by how much time you have, what your interest are and how much are you willing to spend.
If you are going to visit Buenos Aires because it is referred to as the Paris of Latin America, it is not, it is different. That is why I enjoyed my two weeks in BA and going back again for another two weeks in October.
It is funny, I found some portenos when referring to certain areas in Buenos Aires; they compare it to New York City. The residential area I stay in certainly did feel like home.
Tips
While taxis are cheap to used, I only use them to get to a destination on time. Most of the time, I walked and this is where you discover the real Buenos Aires, on many of the streets I walked on. I think this is where something is cheap, like taxis, is bad thing for tourists because they miss out on something interesting because they are in a taxi zipping by it.
Speaking of taxis, use an only yellow radio taxis and always pays in small bills. There been incidents where someone has paid using a 20 pesos note and the taxi driver gave it back claiming it was counterfeit. What the dishonest taxi driver really did is switch the 20 peso note with a fake one. Or if you pay in a large note like 100 pesos you could get back counterfeit bank notes. That happened to couple who was staying at the same place as me because they only had large pesos notes. I saved my small peso notes for the taxis.
Forget the credit cards. I never used it in BA. Also because I was paying for things in cash I was able to negation the asking price. Case in point I was told my leather jacket was going for 900 pesos. I told the saleswomen, that is too high 700 pesos what I was willing to pay. After a few minutes she realizes I was not moving on that price. So I got an excellent leather jacket, far cheaper than what I would have to pay for it New York City.
The 200 pesos I saved was for me the price for two dinners for two, three course meals with a bottle of wine at one of my favorite BA restaurants.
One restaurant I had lunch gave me 10% discount off the bill for paying in cash. Actually I added the 10% to the waiters tip.
I had plans for my trip to Buenos Aires and received plenty of recommendations from people that had visited Buenos Aires, from the BA guide books and newspaper articles about traveling to Buenos Aires. In other words I did my homework, like I would do before any trip.
But Buenos Aires was different for me. I meet in person so many portenos while I was in Buenos Aires. They were giving me recommendation, telling me I should go here or there, should eat here or do not there. I should try this or drink this wine. What ice cream flavor I have to try. In the end, the plans I made before the trip went out of the window.
For example I know I would not have visited three different milongas on the same night, to see the different styles of tango, without being pushed by my new friend I made in BA. Without her I would have seen only one and “thought” I saw tango.
Looking back now the only reason I carry a guidebook, because it had a map of Buenos Aires. No other reason because all the locals were giving me advice.
I think changes to my original plans were due to Buenos Aires does not huge art museums to occupy my time for days. No huge architectural wonders were I spend time was focusing to photograph it at different time of days and angles.
So like an onion when you peal it you find the onions core and in the case of Buenos Aires, the onions's core is portenos.
So if you make it a goal to make friends in BA, the portenos are going to show you the real Buenos Aires.

Bill
William Bert Photography"New Yorkers like to think that their city is the center of the universe, and after spending some time there, I am not so sure they are wrong."
By Bob Krist from Spirit of Place