I have seen plenty of Argentine women looking for "friends" from abroad at Internations.
Never had a bad time at Mundo Lingo. Friday nights at Trova wine bar in Palermo are usually packed with a divers crowd, young and old (majority maybe 25 to 40). The events are posted on meetups.comHey,
You can try some language events like mundolingo. Though the age range may be somewhat broad there.