I am looking for inexpensive lodging recommendations for one night in Buenos Aires and one night in Mendoza. We will be staying in luxury accommodations outside of both of these cities for several nights, so for these particular one night stays, we are looking for something cheap (hostel, AirBnB) but clean and within walking distance of an active nightlife area. The one night we are in Mendoza proper, we'd like to be able to walk to one of the popular wine bars. And for the night in Buenos Aires, we really don't know what neighborhood to be in but it will be our last and only night in Buenos Aires before an evening flight back to the US the next day - so we'd like for it to be in a central area where we can walk to or enjoy the beauty of this city in less than 24 hours.