If you can't easily determine where the leak is coming from (like get the X up on jack stands or something and inspect it from underneath) then take it to a shop to get it diagnosed properly.

Then you can better assess the situation. No matter what they say try and verify for yourself that the leak is actually coming from where they say.

If its the valve cover gasket, you could check the oil separator too. However, if you're not in an area where it gets really cold (in Cali) then maybe not. Of course, we don't know the actual history of your car so ...