For Hawaii, I'd be staying on the beach in Oahu in an Air BNB.
In Mexico, I'd probably stay near Polanco (the upscale area near the city center)
Hawaii would be nice for a getaway, but not that interesting. I'd probably do some snorkeling, lie in a hammock all day, read a bit, watch some giant North Shore surf roll in, but that's about it. Rest and relaxation in paradise.
Mexico City would be a bit more intense. I'd plan to check out some old ruins outside of the city, eat a few world-class meals for a 1/3 of the price that they would be here in the USA, maybe hit up some clubs. Weather should be very comfortable - low 70s.