[QUOTE=channa;7582706]Or AA miles? Neither of them fly that route non-stop, nor do their partners.

Having CO miles, you can fly SEA-EWR on CO or AS, or SEA-JFK on DL. So you actually have best access to that route that you want.[QUOTE]

AA actually serves the route non-stop into and out of JFK, and they code-share with AS on at least one of their SEA-EWR flights. I will give you that CO/Partners have more options, but AA does give you some.

FWIW, AA doesn't seem to have any non-stop availability for May, but they do have availability in F every day in May, except for the 18th, 24th, and 27th Eastbound and the 24th Westbound. On many days, you have several options to choose from. For all I know, they also might have availability on AS, but only the code-share is searchable online. Given that they have an even tighter relationship with AS than CO, I would suspect they would have access to the same (or more) seats as CO.