SGS gets great reviews - see the Starwood forum here on Flyertalk - and $90 is a great rate - where did you find that??

The location is on Sukumvit which isn't really near the Silom nightlife area around Patpong but the SGS is right at a BTS (light rail) stop and so is the Patpong area off Silom (but you may have to change lines at Siam).