This shows it very much depends on individual circumstances.

I had lounge visits which - admittedly - had a "reasonable" value of $5 (typical price of a soft drink at a European airport). But I had others, which saved me full meal - perhaps $25. And occasionally, I spend a full day in the lounge, because I travel often in or to countries with poor flight connections. Working in a lounge then saves me, apart from food and drinks throughout the day, perhaps the equivalent of a day stay in a air-conditioned hotel room - this can easily amount to $200 ... and if you consider the value of the work I can charge to my customers you can almost add another zero ...

So what is the "reasonable" value? 5, 25, 200 or 2000 ?

Yes - I didn't count in my analysis either the cost savings of free wifi or the amount of work I was able to get done in lounges which was worth a lot more.

And you can also have access to a desk and outlet (unfortunately not the case at the DTW main SC now that they have torn out the work areas and you have all these people getting admitted with groups and am ex cards). Shower can also be nice. I do redeyes a lot from Vegas and CA cities. I can enjoy the whole day in the city, the majority of the time I am upgraded (which is great for me on a redeye, much easier for me to sleep) or will have an EC seat with more legroom to relax and sleep better, and when I land I can go in the skyclub and shower and grab a bowl of oatmeal or a bagel and fill up my travel coffee cup and head straight to the office instead of having to go out of my way to go home and shower and change and eat and head to the office.

Where is there a shower at the skyclub?

Most of the major airports SC's that do international flights have showers.

The main SC at DTW has a couple showers (which is the airport I land at on redeyes).

Their locator tells you what SC's have showers:
http://www.delta.com/traveling_check...ions/index.jsp

I will be flying to London tomorrow night and due to my status with Delta will have one hour use of Yotel when I land Weds morning as well so I can at least shower and change after clearing customs. I know some airlines also have arrival lounges in international cities with showers.

It depends on how much and how far you travel.
I've had 60K miles in about 2.5 months one year. Believe me, not having to wait in the TSA line, is a life saver. Not having to wait till the end to board a plane means I won't have to gate check my luggage. I had a co-worker once who gate checked his small suitcase and somehow they forgot to put it on the plane. Not a great thing when you are a business person traveling for work and you don't have your clothes.

As far as First class vs economy, sometimes it's night and day. I can sleep, I can recline. I can relax. I might get free meals. I get treated better. Many times nobody sits next to me. I rarely sit next to screaming kids.

When you fly multiple times per week and some of your flights are 5+ hours, it is worth it believe me.

The no gate-checking is critical - I have had "Roadshows" with clients where we are in 3-4 cities in a 24 hour period and getting my carry-on luggage lost would be very problematic.

JFK SC has 'em. Those are among my favorite lounge shower facilities anywhere. Not as great as the LH/LX FCT/FCLs, but awesome after coming off a redeye from LAX.

I think it's overrated among the current FT population -- many of whom are here for credit card offers, hotel status, etc. I certainly survive without status and while it would be nice, I don't go out of my way to get it because I don't fly enough to make it worthwhile and because of that I would rather save the cash by flying the cheapest fares.

If I were to fly enough and not have to spend too much more on fares to get elite status with one airline (or possibly get matched or a trial offer that would make it worth my time/money) I would probably stick with that one airline despite fares costing a little more. As it is now, I usually end up booking Southwest because it doesn't have change/cancellation and bag fees. The hundreds I save doing this pay for those upgrades where I really want the comfort. I might miss out on some international F redemption opportunities but it's so much faster and cheaper to earn miles through credit cards and other promos that again the money saved is more worth it to me.

JFK ATL DTW NRT are one's that I have showered in.

Not really. I don't stock to one airline, as I have 2 statuses. I do, however, have status spread out over all alliances for maximum benefit.
I also like taking advantage of all the promos that I can, and also understand how to get points from a non FF perspective, but I end up doing both when I am in Canada.
Change fees are usually paid for by employer, however.

I've also been in SLC that has them.

And you call yourself a flyertalker?

Probably all airside - the problem is usually when I need a shower it's when I'm arriving from somewhere overseas and since I have to go through customs first, I likely can't get back in for those, with the exception of the Terminal 4 shower at JFK which is landside but isn't a DL club.

This is exactly why my favorite airport is Frankfurt - Lufthansa has a Welcome Lounge where you can arrive, clear immigration and customs, get your luggage, and then go to the lounge, have breakfast, take a shower, have your clothes ironed (if you are a senator) while you take a shower, and go about your work.

I plan to do just that tomorrow.

I have done that at the Virgin arrivals lounge in London and it's great.