I'd strongly recommend going the apartment route. Even before the peso went into freefall, rental prices were pretty much absurdly cheap, at least if you used a local, "non-gringo" agency and paid in cash. Last time I did that, I rented a pad in Recoleta for US$350. Per week. For a penthouse with a jaw-dropping view!

Also, I'd say most of the hotels you listed are also "gringo-priced." My first and second visits to BsAs about a decade ago were quite enlightening there. The first was at the Alvear Palace for $450/night. The second was at one of the then-new boutique hotels in Palermo that have since sprouted like leaves. I paid $70/night and vastly *preferred* it over the Palace! It certainly had vastly more dining and entertainment options within walking distance.

These days I stay at a friend's place; he bought a pad in Palermo Hollywood and nicely lets friends use it whether he's there or not.