I stayed at the following hotel and I feel like it is one of the best I have stayed in in the country. They also have a nice restaurant on the 7th floor I think and I had some pretty good lobster there a few years ago. It is a bit pricey - RD3600.
Hodelpa Centro Plaza
Del Sol
Santiago
(809) 581-7000
Also, there is a Mariott that I neve have been to but should be good based on the name:
Courtyard By Marriott Santiago
Av V Espaillat
Santiago
(809) 233-8031
Also, the following is a not bad and economical RD2049. They have internet I understand too.
Hotel Aloha Sol, S A
El Sol 50
Santiago
(809) 583-0090