I have 17,000 elite CO miles for this year, and am scheduled to fly to SVO next month on DL. Can't decide if I should accrue CO or DL miles on this trip. I feel like DL has better mileage availability and it's better to rack up DL miles (will be around 9-10k roundtrip), but I think I will get elite on CO if I get the points on CO (right?)

Thoughts? Is elite on CO worthwhile?