My exam went well, thank you.
I'll be so happy if you come to Argentina next year!
I think the best month for you to come is February, because the weather is nice, not too hot but warm enough to go to the beach or sightseeing ;)
Undoubtedly you have to visit Buenos Aires! I know you love big cities and I bet you'll enjoy it. You should hire a car, because travelling by train is really uncomfortable and actually even more expensive than by a car.
When I was visiting Buenos Aires last year I stayed in the "Espacia Suites". The hotel offers very nice and comfy rooms at the low prices.
Can't wait to see you.