I agree with what has been said, *but* if you are a dedicated NW flyer, there is one rather solid perk to membership.

Best Fares includes free membership in Quest. Besides hotel discounts similar to the Entertainment card, Quest supplies $$$ off coupons for NW flights. $35 of flights of $175-274, $60 off $275-374 and $100 off flights of $375 and higher. (Saturday night required - 14 day advance required)

One could opt to join Quest and skip Best Fares involvement - but Quest membership carries a $99 pricetage - substanatially higher than Best Fares.

(BTW, I'm still on the fence as to renewal)