One poster asked how it could be worth 10 hours in coach to earn 10 hours in First Class. It is not that simplistic, with status one normally flies the 10 qualifying hours in FC on the cheapest possible fare. WesternAirlines is correct that the lowest level of status in our present travel environment can be obtained for between $800 and $900. AND-one gets to go to interesting places, not just Pasco, Washington for those prices.
All my travel is now pleasure and has been for the last two years. I have flown in excess of 50K miles the last two years all of it on very low fares. As a NW gold, approximately 90% of my domestic travel has been upgraded to first including domestic segments in conjunction with international travel. Unfortunately, my international travel is not upgradeable because of use of cheap tickets. That is the anomoly of my chosen program. Had we chosen UA, we have a gift source of SWUs. In the two years the account has grown by over 300k miles which is enough for 4 RT Business Class tickets to Europe. Assuming an $1800 investment for each year, the total investment was $3600 which earned travel that would conservatively cost $8000. And-We would have traveled anyway! Due to the economy, we may use our miles to travel in comfort at no cost. That opportunity would not be available if we had not made it a point to accrue the miles in the first place.
Circumstances and analysis of the situation provides the answer. Taking a mileage run is certainly not for everyone.
The interesting thing is that often a domestic free ticket is earned just as the result of one vacation trip. Its just a bonus making the original trip even cheaper.
The intangible value of status, as has been pointed out, is probably more significant than the economic gain. Preboarding, FC checkin, being treated somewhat better have enough value that MrsOpus insists on traveling at least 25k miles per year to maintain her silver level.
As long as your butt is going to be in a seat, it might as well be as comfortable as possible getting from point A to point B.