you may consider staying in Recoleta. it is much closer to the microcentro, has less of a night life but more day scene, nice little squares (piazzas) with coffee shops and small stores.
Teatro Colon, Casa Rosada, Recoleta Cementary, Puerto Madero, Calle Florida, Cathedral and San Telmo sunday market are all walking distance.
Safe at night.
And the architecture is way better than Palermo.