agree with the above. i am lifetime platinum on AA and had been executive platinum/concierge key for almost ten years before moving to london. while i still have about 6-8 trips to the US each year, i will say that i am treated far better on AA as a GGL than i ever was with my AA status, oddly.
with resepect to the AA 500-mile upgrade certificates, (or even complimentary upgrades as an executive platinum), they were almost non-existent on my primary routes--the transcons--and had maybe a 70% success rate on other domestics. of course my account still have about 22 500-mile certs which are more than ten years old and will remain there probably for another ten.
finally, the spend threshold may make things complicated for you. they introduced that the year i moved to BA and while i know i'd easily reach that, i dont need an added metric to concern myself with! having been with BA for four years now, i just think overall i get more with my BA status while traveling with AA than the reverse.