As a PLT, you get the 500 mile minimums (that you also got a a gold, so no big increase there), but you also get:

• Access to business class lounges and checkin when flying international (even when flying coach). IMHO this is a huge benefit.
• Access to advance seat selection and exit row seats on OW partner airlines (makes international flights much more pleasant)
• Much higher priority on standby and upgrade waitlists

For domestic itineraries, the last bullet is key. I fly a lot of DFW->TUL. The flight I want to book is typically $50 more expensive that a flight 3 hours later. I always buy the cheaper flight and go standby for the earlier flight. With the PLT status last year, I only missed it once (out of ~18-20 trips). Kind of off topic but, this has saved me about $1k.

This is all fine and good, but where the status really helps is when you hit EXP and get the 8 SWU/EVIPs. With these you basically get a free upgrade from coach to business. Just for the sake of a mileage run argument, you could book DFW->SFW->ORD->PVG at deep discount coach and upgrade the entire route to business, enjoy first class lounge access along the way and earn 10,350 EQM. Then you could repeat this 7 more times for a total of ~82k EQM.

This is sort of an extreme example (although, I'm sure someone here has done it) but compare that to the equivalent mileage run you would have to do in coach. Yep, much easier to maintain status.