In its continuing efforts to be poor at communicating benefits to members, Amex has a best of British promotion going at the moment that it didn't tell me (or any other Plat/Cent holder I know) about.
I found out about it in the Departures website which Platinum and Centurion members have access to. I get the impression most of these benefits are geared to US cardholders, but they are valid for all countries.
There is a lot of useless junk here (like a free cup of tea if you buy £5,000 worth of jewellery) but there are some good bits, like unlimited champagne at the Rib Room in the Carlton Tower
http://www.departures.com/britishexcellence/25.html
....I think I know where I'm going for dinner!