Thoughts:
1. Can you not waitlist for LAX-LHR in BF? Perhaps splitting the tickets to get a better waitlist chance?*
2. It is not worth the extra flight LAX-EWR in E+ to enjoy a relatively short BF flight EWR-LHR. Maybe if you got the 752s in BF, that's another thing.
3. E+, if you are stuck there, can be mitigated by aisle/window, aisle/window seating.
4. Nothing prevents you from sitting in E+, and if #1 clears, letting your kids/wife enjoy BF.
*Yes, the fact that the status no longer transfers is something to consider.