In light of the financial health of the airlines and some sort of CO/DL venture in the mix for the future, which is the best route to take: paying for an annual PC membership or simply paying the fee for Amex Platinum?

If you use airline lounges right before/after flights on their airlines and never any other time (i.e.: meeting other passengers, holding meetings in lounges, etc.), is there any reason why you'd buy a PC membership rather than simply get an Amex Platinum (which offers access to Continental, Delta, and Northwest clubs)?

I've searched the threads here... and I've seen issues with non-CO European and Asian clubs of airlines with codeshares... but other than those international issues, is there any reason why on club access alone, the Amex Platinum isn't a better option than the CO PC membership?