I respectfully disagree.

What I have discovered is that to take advantage of ffm upgrades you have to spend 125%-140% or more of the lowest coach economy fare. Then the upgrades you use typically cost 50% of the ffms you must spend for an outright business class ticket. It's a waste of money and ffms.

An example. We recently traveled from/to SFO/AUA [Aruba]. The lowest cost restricted advance purchase economy class ticket was running $700 or more. The cost of a ffm economy class ticket was 30K ffms. The cost of a ffm business class ticket [really a first class ticket because the aircraft used only offered two classes of service] was 60K miles. We opted for the 60K mile outright business class ticket.

We had some friends we were meeting [traveling the very same routing as us] who wanted to use ffms to upgrade from coach class so they could accrue the miles attendant to their coach class travel [about 7K round trip]. They had to spend over $1,100/ticket for a higher priced economy class ticket to use 30K ffms/each [15K ffms each way] to upgrade to business class. Thus our friends in essence paid $1,100 for 30K ffms; a terrible conversion rate in my opinion.

If you're going to use ffms to upgrade, in my opinion you're far better off just redeeming enough ffms to secure a business class ticket outright rather than purchasing an upgrade. I know of no program where it costs you less than 50% of a plan ahead business class ticket and the unnecessary higher cost you must pay for the additional 50% of travel is just not worth the tariff!

The biggest bang for your buck is purchasing business class outright with ffms!