Platinum benefits

1. Guest in lounge
2. Access to the 51st and Green if traveling to the US
3. Access at ORD and SFO AA lounges when flying EI
4. Access at BA T3/T5 LHR if flying in from DUB/ORK/SNN via LHR to a BA flight, BA ticket with EI flight
5. One upgrade per annum to business
6. 25% more avios vs Silver

So if you fly to the US or fly via LHR with BA then its worth it, but it is heavily biased in favour of US bound traffic