For someone like me, who hasn't really paid much attention to the Amex Gold card/Member reward points in the past (until someone cross posted on the bmi forum), how does this fare against my current cards - Is this a one-time offer (use then drop after the 20k points come in) or do people actually use this card regularly to their own benefit?

To put it in perspective I have an Amex cashback (which I rarely use after my first year's large cashback cheque) and a BD Amex (my main Amex card for those juicy airmiles), then a Marriott Visa for those places that don't accept Amex (and Marriott hotels).

To put it in perspective I tend to spend about £3k/month on the Amex and about £2k on the Marriott.