Kids N' Coffee
Here's my opinion, for what it's worth...
If you were just to have an area where young kids could play, draw, etc. while the adults had their drinks and could relax, I could see that concept working. If you are talking about making it more like a daycare-ish, McDonald's Playland area, I'm not so sure that would work.
Now keep in mind that I don't have kids of my own (yet), so my opinions are probably skewed towards adults rather than kids. But the details that you provided a very sketchy right now; if I were to see a more detailed business plan about your idea, I could probably be convinced of it working, and working well. I would say that you would have to evaluate if your area could use a facility like what you are proposing, or if it is diluted enough. I could go on, but its a moot point without more details. I do hope that whatever you decide to do, that you are successful!