Nothing like a discussion about a super-tier above CO plat to get the blood boiling on this board. It's been discussed ad nauseum here.

Like the OP, I will fly at least 150k miles this year, any maybe closer to 200k. I have already reached plat status on CO for 2008, so I am flying on DL to re-up for Plat status there as well. (nb: my DL Skymiles AMEX card spend will get me at least 10k and maybe 20k EQM's, so I'm off to a good head start).

Why do I do try to qualify for Plat on DL and CO? ? If I fly DL on transcons (or anywhere domestically for that matter), I get upgraded about 95% of the time (as a DL plat). I realize that folks think the DL product is inferior, but the upgrade is great, especially as it is almost guaranteed to clear, and in the NYC-LAX market I'd rather fly DL than CO. When that DL upgrade clears 5 days out, makes travel day so much less stressful. Sorry. Also, DL has excellent partners. All those miles I stockpile can be put to good use.

I keep status on CO because the BF product is excellent, and if not flying on a BF ticket, I can upgrade with miles and $$ -- not the case on DL. I've read with interest the many posts and threads here about the difficulty others have had in upgrading to international BF on CO, but my mileage upgrade success rate has been almost complete.

So, bottom line -- if you are flying substantially more than 75k miles on CO this year, no reason to spend your travel dollars on CO beyond that milestone. Lost revenue for CO is something one would hope they'd think about.