Here is an idea for you. How about offering food for kids? Ask my daughter what she wants to eat at McDonalds and do you know what she'll say? Toys! She said she "don't like McDonalds mommy, I like toys". So Im spending money on mcnuggets so she can have toys.
I also know a few couples with kids who dont go out to restaurants because the restaurants dont have anything to kids. I personnally make mud pies with Graham Crackers and Lite Chocolate pudding garnished with a gummy worm for dessert. The kids love it. Then there is green eggs and ham for breakfast. Im sure we can come up with some good stuff for kids to eat. And if the kids will eat the parents will come. Im sure you know how many people have kids in this country, and as parents Im also sure you know that sometimes we really DONT WANNA COOK!
We also bring our kids into the diner with us. So the parents see that we are really ok with having their kids so now they are coming in and recommending us to friends. We'll even babysit if they have to go to the bathroom and their kids have someone to talk and play with so the parents can eat. We also have toys their to distract the little ones if mommy forgets.