Depending on your required routing, sometimes a connection can be quite cost-effective. For example, you may find that JFK-LAX-PDX costs quite a bit less than JFK-LAX. Try other west coast cities too, of course.

This tip is more helpful if your final destination is other than LAX/SFO.

On the return, try tickets from LA to your east coast destination on to the Caribbean. Those are international tickets (duh) and full fares therefore come with free unlimited stopovers. Could get LAX-JFK-[pick a Caribbean destination], for example. In my experience these flights can be considerably cheaper than just LAX-JFK point-to-point -- i.e. the final Caribbean segments gets through in for essentially negative cost.