Kudos on that! Best use of miles in F! I'd rather buy the ticket for a transcon if going in Y myself.

Have to ask though - did you really do a thorough search for EWR-PHX dates in September on US? There's plenty of Y availability on the non-stops that I can see on random September dates I've checked. I'd rather burn them in F myself but if you really wanted Y and had at least a day or two of flexibility on each end, I'm seeing plenty of both US and CO non-stop options in Y at the "low" rate from EWR and JFK.