It is simple to earn delta status and miles. They hand them out like candy. I fly 100% for leisure. I have diamond status thanks to Amex. I use both companion certificates I earn with Amex on expensive transcons that are now not upgrade eligible or for two travel companions to keep me upgrade eligible.

As far as miles, I flew JFK-gru rountrip for 100k. It was great. I just cashed in 640k for four seats in business: JFK-lax-syd (stop)-akl (destination) per (open jaw)-Mel-lax-JFK. I already have another 200k.

I appreciate the SPG crossover rewards. I've gotten some decent upgrades already with "plus" and I'm now gold with them.

I earn most of miles through credit card spend, and I churn non Amexes.

Delta's booking process is a pain, but if you know the rules and are flexible, it's just fine.