Watch out for <100% EQM when flying discounted Y fares and crediting to A3. I thought about switching to A3 recently, but decided not to because some discounted Y fares only earn 50% EQM.
LAX
I think you are right about this. My problem is that my employer forces me to fly UA TATL, and A3 has one of the only programs that seems to give 50% for discounted Y fares on UA. Those trips are usually my big earners. I tallied all of my segments for the year with respect to various programs and it looks like BMI might be the optimal program for me with respect to getting *G. Only non-earners for me are K fares on LH and L fares on SN.
Other option is to take an expensive MR on AC to get my five segments.
As for the value of *G, it certainly helped in the past with baggage allowances, particularly when taking the entire family. Lounge access is nice also.