bluejay says it's CP, is this any different?

CP=AC now, the only difference is that they still operate their own aircraft. You can tell whether you are flying CP or AC aircraft simply by looking at the flight number. CP aircraft has 4 digit flight numbers beginning with a "3".

Is AC's Executive First any different/better than CP's equivalent?

AC's Executive First is equivalent to CP's Club Empress on 767-300 & 747. I personally think that the Club Empress seats are more comfortable, however, AC has a better entertainment system especially if you get one of the on demand entertainment system.

I am flying from Boston and have to change somewhere, so this option seems interesting?

Where are you flying to? You will most likely get the domestic J (Executive Class) service if you are flying domestic/transborder flight unless you are flying transcon.

If it's CP, does that mean I can use AA miles, as well as UA miles?

No, you can't use AA miles anymore. Agreement between AA and CP ended long time ago. You could use UA miles to fly AC (or CP) since all CP operated flights also uses AC flight numbers now.

[This message has been edited by Empress (edited 03-11-2001).]