[another2]

As far as I can tell, so long as you are accruing new miles to the account each year, the miles "stay good." It is only when you stop flying for a long period of time that they expire. We also have the Delta Skymiles membership. And we opened a Delta Skymiles American Express account when we travelled. Then we accrued miles for paying for our plane tickets and Marriott hotel stays and, at the same time, received Delta Skymiles from Marriott for staying there and from Delta for flying. We accrued a ton of miles which we used when we got home to visit relatives to show off the new children. Last year my husband took several trips on Delta affiliates and earned Delta miles -- enough to fly 5 of us across country on vacation this summer entirely on miles.

Delta has a new system of letting you use miles and pay. So if a ticket is cheap, you can just use miles. If you are booking last minute or during a busy time and the ticket price is expensive, you can use miles and pay some in cash. Since they have started doing it this way, I have not had trouble getting a ticket unless the plane was completely full. In fact, I booked a ticket this way the day before I needed to fly out to California this spring. A $1500 ticket ended up costing me miles plus $79 -- mostly because it was so last minute. I understand their program is changing again -- or has just done so. I am not sure what changes are being made, but we have had terrific success with them so far...