For how many days are you going to? renting a car is not a bad idea if you want flexibility, I used Hertz Argentina (Hertz.com.ar) and I paid like 22 dollars per day in January. Uber is cheap, but sometimes you have to wait in some places, specially in he afernoon.

If you like meat, check out Alto el Fuego located in City Center, or Madurado (you can finally find it now on google).

Regarding both hotels, well if you have Bonvoy points, Arlequín is your best option, besides Llao Llao is very crowed in the afternoon during Tea Time (4:30~7pm)