I know that Coach has different fare types, and that some of them are upgradeable, and some aren't. What I can't seem to find is which are the upgradeable ones...... I specifically fly Delta and United - but I wanted to see if I could buy the coach tickets - then upgrade with miles, but I'm not sure which coach seats I would need to buy! Could someone point me to that information?

Why don't you call the airlines directly? I sometimes find that is the easiest course of action.

For Delta, K and higher for domestic/Canada, M and higher for everything else.

Hi Debi- M/H fares on United international flights are less expensive, but require more miles to upgrade to the next class of service (from economy to business) than Y or B fares.

M fares are upgradeable on Delta. As with United, international M fares on Delta require more miles and are less expensive than Y/B.

Info is available on websites of both airlines. When searching for fares on the websites use the drop down menu to select desired booking class.

When booking on Delta I always use an agent so that my upgrades are confirmed. I also do this with united but not 100% of the time as their website tells me upfront if upgrades are available. I think it is worth paying the agent booking fee to ensure I get the upgrade I want.

Just about any United economy fare you can buy via the website is now upgradeable using miles--domestic and international. But, there is a cash co-pay required in most cases; e.g., $250-$500 each way for transatlantic fares M and lower.

Information here:
http://content.united.com/ual/asset/..._052010_v2.pdf

And here:
http://www.united.com/page/article/1...Upgrade+Awards

Thank you guys so much!!! For some reason, I was getting in a hole trying to dig through all the options, and you just made it so easy for me....

And before you buy an M fare on Delta make sure the Business Fare isn't just a cheap. The M fares are HIGH and I have found that the advance purchase business fare can sometimes be fairly close so it's not worth using the miles!

ms_go and Carol both make good points. I had forgotten that any fare is now upgradeable on United, and for my upcoming trip to Asia on Delta a business class fare costs the same as an M fare.

Yeah - I saw that.... For what I have to pay for the upgradeable fare, it just is easier to just buy the business fare from the get-go.....