I have searched quite extensively but have not found an answer for my situation on purchasing different fare class tickets.
I fly all domestic, NY-FLA, NY-west coast. I currently have no Medallion status but will make gold sometime this year. I book trips with AMEX reserve card.
My basic question is why would I search a higher class ticket and pay extra? Without any medallion status, currently, I pay extra for economy comfort.
I checked http://www.cwsi.net/delta.htm and it seems like the main advantage to buying a higher class ticket is to get an upgrade. Is that really necessary? after making a certain medallion class aren't you entitled to an upgrade regardless of fare class if available?
Also, I don't understand from the chart the difference between "published MQM" and "unpublished MQM'.
I obviously want to maximize my MQM. Since i don't fly all that much I'm relying on my spending on the amex reserve to help me get to gold. Any advice would be appreciated.

This thread to should help, even though it's probably a little outdated.

My basic question is why would I search a higher class ticket and pay extra?

A few reasons, but i'd argue that it's rarely done by the majority of medallions.

1. A higher fare on a coach ticket puts you ahead of those within you medallion level on a lower fare for upgrades. The exception is full fare(y) in which case you trump everyone not on a full fare or SWU

2. Upgradability - certain fare classes are required in order to upgrade your ticket with miles. For domestic flights, it's K fare. This is not important to most people, as there is very little inventory for this sort of upgrade. So it's unlikely to work.

3. MQMs - Y and B fares(and formerly M) earn an extra 50%(150% total) MQMs. First/Business tickets also earn 150%, with the exception of F,J, which are full fares, earning 200%.

The unpublished vs published on that site look incorrect. Any fare on dl.com is a published fare and gets full miles and mqms. Published fares can be bought on other sites as well. Unpublished fares cannot be bought on DL.com and are typically sold through low cost deal sites.

No medallion is entitled to an upgrade with a coach ticket. The one caveat to this are UP fares, but that's sold as a first class ticket.

OP - have you tried searching "delta mqm fare classes" on google. This is the first result, and basically says everything i did. You should work on your googling skills:
http://www.delta.com/content/www/en_...ith-delta.html

And the second result for "delta fare classes upgrade order":
http://www.delta.com/content/www/en_...-upgrades.html

Thanks for your clear response. I will work on my Google expertise. I guess I had the right answer and it is just a matter of preference as to whether to pay up in the hopes of jumping someone for an upgrade. I guess depending on the price of a higher fare code it may be beneficial to pay up for additional MQM's. It would be interesting to know what other gold medallion members would be willing to pay for a chance to upgrade. I'm pretty happy getting a seat up front in coach and early boarding. It seems like a lot of work to start comparing all the different fare on the delta website.

Upgrade priority goes by fare class (after medallion level). Also, some upgrade instruments (SWUs) require a particular fare class.

If a fare is published (e.g. on Delta's webshite) you get full MQMs. If it's unpublished (e.g. free airfare with a cruise, or buying a vacation including airfare from a third party) you might not.

I highly doubt that very many would, especially if they are paying out of pocket(ie not for business). It's much more effective(with regards to getting upgrades) to book flights during off peak times and to pick flights with the most available F seats. You check the number of F seats by going to flightstats.com and searching flight availability.

I just searched LGA to MIA and the 1:45 and 3:22 have 7 seats in F, while the 6:50 has 3. Much better to pick the earlier flights or SDC to them in this example.

There is one other thing I forgot to mention. A higher fare class makes same day confirmed changes much easier, as the higher the fare, the more likely the availability.

In all of this you're certainly paying with more than necessary for the ticket in the hope of receiving an uncertain benefit with higher probability. You're basically buying a lottery ticket with unknown odds, where there might well be no chance of receiving any benefits (except if you purchase a fare that yields more MQMs).

Thats the way I see it. but I have read so much on the forum about fare codes and people looking to buy up fare codes. My guess it is more for the business traveler. Didn't make much sense to me.

SDC them??? a lot of abbreviations on this forum, trying to figure them all out.

"I just searched LGA to MIA and the 1:45 and 3:22 have 7 seats in F, while the 6:50 has 3. Much better to pick the earlier flights or SDC to them in this example."

If someone else is willing to pay, you would earn more MQDs for sure and maybe more MQMs, plus the higher fare class might help you to get an upgrade and/or SDC.

SDC = Same Day Confirmed, meaning that you change your flight either by phone or at the airport for a different one on the same day without paying change fees.

thanks for everyones response and help. Looking forward to becoming GM this year and getting some perks.