I'd suggest the Jianguo Hotel. It's on the segment of Chang An Avenue where many full-time and part-time pros walk the street. There is a salsa club not far across the street from the hotel in the Hua Qiao (overseas Chinese) village area, but the club is not right along the street, about 50 meters from the street behind the buildings, but plenty of lights to show it's a night life spot. There are other clubs in the general area. From there, you can take a short taxi ride ($3) to Kempinski/Hard Rock/Sheraton area.
There are two other areas worth visiting, although it's a hit or miss. One is the Hou Hai bar street, the other is the Melody disco club on Zhong Guan Cun Boulevard in Hai Dian district (about $10 taxi ride distance). Both of these places have pros and non-pros. The latter has a younger crowd (college students or post secondary youngsters). A couple of KTVs on the south side of the northeast 4th Ring, near the intersection with the street where Sino/Japan Friendship Hospital is on, have some of the best looking girls (yes, better looking than the ones in Sheraton) but these KTVs are pricey.