Hi there.
I definitely don't have terrific chops, but let's see if I can be of some help. Actually, how much help I can be is very debatable because EVERY TIME I go sing, I make sure I do at least one song I've never done before. The songs I've tried are either songs I personally have at home already or have heard frequently enough over the years that I know I can at least BS confidently. 
The songs I've done that were the easiest for me to pick up are funk/R&B records. Two of the songs I do the most often are "Da' Butt" by E.U. and "Flash Light" by P-Funk. These have been among my favorite songs for many years, and even before I started with karaoke I had listened to them enough times that I knew them like the back of my hand.
The hardest songs for me to learn, among those I've done, are 3 songs I love but unfortunately have varying degrees of success with -- "Don't You Worry 'Bout A Thing" by Stevie Wonder, and both "Year Of The Cat" and "Time Passages" by Al Stewart. Those songs have VERY full and rich instrumental arrangements but have HUGE swings in pitch from one lyrical line to the next. "Don't You Worry 'Bout A Thing" is a song I have literally never heard anyone other than Stevie himself do well, including me.
The Al Stewart songs are, fortunately, songs that I do well, but it's VERY easy to screw them up if I'm not careful.
"Waterfalls" by TLC would be a great song to work with at first. It'll definitely get people moving, it's old enough by now to not be overdone, and it's not too challenging vocally -- to the point where I, a blond, blue-eyed white guy, sometimes do it.
It really is about showmanship and entertainment value more than anything else. One of the best-liked singers where I usually go is an older fellow who actually can't sing worth a damn if you judge by a strict technical standpoint. However, he usually shows up in costume (a hideously loud plaid suit or a tuxedo) and tap-dances to many of his songs. People go wild for him.
Good luck!