My dad's quite happy with DN's coupons - at about 3500/coupon they're good value. Of course dad travels mainly for pleasure, so being right on time is not critical. Besides, he's glad that he can nominate another 3 people to use the coupons - so he's nominated my mom, and me and my BIL.

The thing he likes is that there are no "capacity constraints" on DN for coupons - if there's a seat available, he gets it. I hear some of the other airlines have capacity constraints for coupons (at least 9W's J class coupons have capacity constraints built in).