I've stayed at Keio Plaza, although not at BW. In Shinjuku, I personally gravitate towards large hotels to the south and west of the station (Century Southern, Hyatt, Keio Plaza).

I would second what beep88 said above. Keio Plaza is a large, full-service hotel with nice rooms, albeit a bit dated. I don't know firsthand about BW's rooms, but one negative with BW is that it's a bit more of a trek to the station vs Keio Plaza. Unless you're traveling with little kids or something, I wouldn't worry too much about BW's Kabukicho location or the touts. That area should be pretty safe.