If you have a Diners Club card you can convert FF miles into MAR points. The exchange rate is lousy, but you can do it.

Start by transferring FF miles from your airline FF account to Diners, converting the FF miles into Diners Club Rewards points on a one-for-one basis. You must do this in 10,000 FF miles/points increments. http://www.citibank.com/dinersus/clu...s/mls2pnts.htm

Next, convert Club Rewards into Marriott points at the rate of 2,500 Diners Club points for each 1,500 MAR points you need. http://www.citibank.com/dinersus/clu...m/guestpgm.htm

Thus, it would take 30,000 FF miles to get your 18,000 MAR points.

This is not a great deal.

Assuming you believe the FF miles are worth about two cents each, the 30,000 FF miles are worth about $600. Based on the way you are using the MAR 100K certificate, the MAR points could be worth as much as 1.2 cents each (based on a nightly rack rate of about $400) or a total of $196 (18,000 X 1.2 cents). Trading in $600 of value for $196 of value isn't a great deal, but it might be better for you than paying retail rates for the villa!

If you really need to do this within a month, there isn't enough time. Diners says it takes as much as 45 days, but in fact it normally takes less. However, if you already have enough Club Rewards points, you can omit the first of the two steps and may be able to get the exchange done in time.

Note: You can use this same methodology to trade FF miles in one airline's program for FF miles in another program. However, in doing so, you will generally wind up with half as many new FF miles as you trade in. The notable exception is British Air FF miles. A current Diners promotion allows you to exchange FF miles from other airline programs into BA FF miles on a one-for-one basis, by following the indicated steps.

[This message has been edited by Dave M (edited 06-12-2001).]