If the airline is allowing you to book that flight combo then they consider the connection to be valid. However, AMS does secondary screening for US flights at the gate - I imagine if you are there then no problem. I haven't been through there in years, but its a very large airport, although well-run.
I avoid CDG like the plague - we were going to Sweden via CDG one year from the US for Christmas and there was some industrial action and everything was cancelled except, oddly enough, Scandinavian flights. Its a very strange layout as well - AMS is a better option of the two.
I would wait until after the holidays as most flight sales are between second week of Jan and first week of February. LAX is a tricky, tricky market to get a deal on, we are looking for flights for June right now as well. If nothing good comes up out of LHR then we will probably do the usual trick of flying to Stockholm to get the SAS flight - their premium economy product is outstanding and the price is almost the same as economy out of London. Sure you have the add-on cost of the transit flight and the overnight hotel, but for decent service, lounge access, extra luggage allowance, and not getting squished into a tiny area for 12 hours, I am ALL for it.