Hi @saritrace and it’s lovely to see you back posting on the Forum 
If you were only travelling there for a week or two like we have, then yes I would suggest taking US dollars is the best option. However, in your case, due to the length of your stay, I would advocate seeing if the bank that you use at home has an affiliation or an association with a bank in Buenos Aires. This might allow you to draw funds directly from your account at home whilst you are away.
Another option might be to actually open an account with a bank in Buenos Aires but you would need to look in to this.
On another note, I have a couple of great restaurant recommendations for you. We have always enjoyed The New Brighton and El Establo, two great local restaurants. There is also a great restaurant/coffee shop called Cafe Florida on Florida.
Also, for reference, as a member you can also add your TrustedHousesitters profile on to your Forum profile by following the attached link, should you wish. This will then enable others to offer you helpful advice and feedback.
If you are unsure how to do this, or if you have any questions at all, do not hesitate to ask, we are all more than happy to help.
Have a lovely time in Buenos Aires 