By far the best hotel is the Gran Almirante.
Then you have Aloha Sol, and another one down town with a casino across the steet, It used to be Hotel Santiago Camino Real but it has another name nos. Calle Mella.
Hotel Jardines is new, clean and less expensive.
If you do a search of Night life. clubs in Santiago. You should get a long list of places to go...Bars, Clubs and eateries are great in Santiago.
Dress properly, this is not a tourist city. Jeans/khakis, T-shirt or polo shirt is fine. shoes not flip flops...
Have fun!!
HB