FWIW, the attached is a fairly helpful tool showing the OW benefits:
http://www.oneworld.com/ffp/my-oneworld-tier-status/

It is very clear over lounge access for example. I keep it handy as a link in case of future dragons; but not needed it to date as I've simply asked my status be checked thru their systems when not in biz (eg. I ask they check I am showing OW Sapphire, not BA Silver)
Baggage is more complicated as it seems more about FF to FF reciprocal arrangements than a OW benefit (of course 2 bags to a OWE should be a OW benefit but it seems it isn't).

Seating? AA.com seems to allow me to choose before payment, so that's what I use! I suppose if it doesn't play ball I'd go in Plan B,C,D mode.