It reallly depends. I have a separate jar for pennies ---- one of those huge bear jars that animal crackers came in. I think once that's filled, it *may* be $150 in pennies. As for my regular coin jar, I would think about $300-$500 a year depending on how you do your saving. For example, I NEVER give cashier coins, even if my item comes to $3.07. I just hand them bills and all the change will go in my jars. Also, when I do my bottle returns, I ask for it all in change and that goes in my jar as well.
I've used my jar money for Broadway show tickets, Christmas, outlet shopping. We have yet to take a vacation but when we do start planning one, I will absolutely use the change jar strictly for that so we'll have fun money for souveniers, etc.