How do *you* set and enforce limits for kids of different ages

I have 4 kids and I do set different limits for each. My oldest gets more priviledges and biger consequences for bad behavior than my younger ones do. I often hear from my kids "that not fair" I say when your older you will get the same priviledges and punishment so dont rush it. I think its unfair to try to punish them all the same since the older one knows more what shes doing wrong (since Ive told her a million times :)) you should do what feels best for your family since noone knows your kids better than you do.