Originally Posted by
shorthauldad
I collect with BA not with AA
A couple of points of advice for next time.

First, post in the forum whose
program you're asking about; if you're asking about BAEC earn rates, or you're looking at it from a BAEC perspective, I'd suggest posting there. Second, it's against FT TOS to cross post the same or similar questions in two fora.
it's looking like there's actually no benefit to me to book via the codeshare, unless it definitely allows me through-checking of baggage and booking direct with WestJet wouldn't... (?)
AA and WS have an interline baggage agreement, so you should be able to through-check your bags in either case. It's more likely that the agent will know how to do this if you're booked on the same PNR, but that isn't a requirement--if you take both itineraries with you as you check in at JFK, you should be able to through-check them from there. Even if you're totally SOL, it looks to me like WS allows one free bag anyway, so if you cannot get them through-checked just collect and recheck them in Vegas.
Given your goals of attaining BA status, have you considered other crazy stuff, like JFK-LAX-YYZ all on AA metal? You'll earn more Avios and TPs that way... Just a thought.