Being based out of the greater LA area, you'd be well-positioned for some of the better/easier SkyMiles redemptions--namely, VA to SYD/BNE and CZ A380 to CAN and on to Asia/Australia/New Zealand.

LAX/SNA are pretty difficult DL markets--when I was a GM, I found I was able to snag upgrades on the SNA-ATL redeye here or there (which now does not exist in the Winter 2012/13 schedule), but it wasn't until I became a PM that the upgrades got much more plentiful. If you're going to be flying to the east, I wouldn't expect so many upgrades from SNA-ATL until hitting the PM level. However, if you can fly LAX-CVG/MEM through to your final destination, you should have much better luck as a lower level medallion flyer.

However, in Y, the craft from LAX and SNA are among the nicer experiences. Most of the planes doing transcons from LAX or SNA have AVOD, and some internationally-equipped planes fly from LAX at times. The internationally equipped routes are nice, except if you need to use Wi-Fi (which I often did).

I've found DL FAs very friendly, but ticketing/gate agents at LAX are very hit or miss.