When it comes to flight redemptions these programmes seem to me to be less valuable than in the past.
I remember the days when my flying with KLM and Northwest allowed me to redeem Flying Dutchman points for flights between London and Amsterdam which were completely free.
At the other extreme, in the last year I've paid almost £400 on each of a number of occasions to BA in "taxes, fees and surcharges" when redeeming BA Miles for trans-Atlantic travel. Given airlines' sophisticated revenue management systems, I'm sure that's income for seats which would probably have gone empty. What one hand giveth....