What is the appropriate tipping in BA in restaurants, taxis, etc. What if hotel has a car for pick up from the airport to bring you to the hotel... what is the amount of tip you should give? Any advice on this would be great. thanks

People in Argentina are still in a pretty serious economic crisis. It is not a third world country, but people are struggling. Prices are cheap.
I make it a rule of thumb to tip a minimum of a couple of bucks...usually a little more..for things like taxis and drivers. In restaurants I do the same as I would in the U.S.
It will be greatly appreciated, but not demanded like many places in the world.

Good Luck.

The norms are:

Restaurant. 10%
Taxi. No tip is expected. For good service, a peso is sufficient.
Private Car from airport. U$1-2.

If you want to tip more, you certainly can...but it is not necessary.

In restaurants a 10% tip is customary, but if the service is excellent 15% to 20% is appreciated. I just take with me $1 U.S. bills to hand out as tip to maids, concierge, taxi, etc.

50% would be appreciated too, but 10% is usual and custumary in Buenos Aires, unlike the United States where 15-20% has become the norm.