Thank you for the response.
I ended up booking a similar flight. The return from SAN > MEM > AMS > WAW is the same.
However coming in I am going WAW > AMS > LAX > SAN. But by this route I am able to get 3.5 hours at LAX? I'm assuming that should be sufficient to clear customs right? I have more options just in case not.
Going back though, would I clear customs in AMS or WAW? I have just about 2 hours in AMS and I want to make sure I'll be okay if it's needed there.