A lot of the points have been covered, but I’d just point out that if you are flying a decent amount on AA domestically, having platinum will go a long way with IROPS. If Non-AA OWS are treated similar to platinums, then it is moot, but the last thing you want to have happen is either waiting hours on the phone (could happen anyway), low on the standby list or on some lengthy airport help desk queue. Granted, the latter could be avoided if you have access to an admirals club etc, but this has been my primary reason for not also going for Gold (or even GGL) in addition to EP. I also typically fly over 100 segments a year domestically so having coverage and a very good shot at upgrades when I don’t buy up due to a high LP point balance matter.

Platinum upgrades on domestic flights are so hit or miss at this point. BOS-LAX / JFK-LAX on a Monday evening may have a few on a list with everyone clearing (big step up between economy and flagship business) whereas MIA-BOS on a Tuesday night may have 30 people on the list with no one clearing because the buy-ups are so cheap.