Delta Reserve Card will definitely improve your chances. Even though fee is steep, here are the advantages -
- Upgrade priority
- Free companion ticket
- Free skyclub access (from next year access granted thru diamond status is going away)
For me just the companion ticket on A fares makes it worth it.
As many posters have said don't connect thru ATL. Try DTW or MSP, even they are not so easy to get upgrade on.
There is one thru RDU and a non-stop redeye from LAX these are your best bets as a diamond.
Try to buy as late as possible so that you have a higher fare class and finally one sure shot way to get you into F - Buy it! you can buy a coach class fare for expensing and then call and buy up F with your own money.