What a fantastic idea creating a kind of karaoke hotel! You rent a room and get your own karaokemachine. You can order drinks and there's a great buffet too. Someone ought to make this an international franchise! Great fun :D
Dress Code: Casual, the best accessories is a group of friends :)
You can go to western bars in Beijing or anywhere in China for that matter and have a good time, but it isn't the way most locals do it. China like much of East Asia loves karaoke.
This is what to do. Grab some friends, the more the better. Try to grab a few Chinese if you know some or befriend them (it could happen) and head to the nearest karaoke palace. The are everywhere. You can read the English part of the sign that say 'KTV', thats the place.
Inside you and you friends will have a private room. You order drinks and usually food. Yell your lungs out, you'll only be embarassed in front of friends, not strangers (which might be worse).
It's a good time for most.