If you want dinner time entertainment, try the Marrakesh for belly dancing:
http://www.washingtonpost.com/gog/restaurants/marrakesh-palace,796793.html

I don't know off hand of a place that does karaoke but I'm sure there are some.

If you want to go dancing, I'd choose where you want to go and find a restaurant near by:
http://www.washingtonpost.com/gog/best-bets/best-dancefloor,71171.html

I am organizing a night out for the ladies at work. A fun group. Ages range from thirty to fifty. We want a fun night, karaoke or dancing and a good meal. Any suggestions for such a place in the D. C Metro?

TIA