Join Date: Sep 2005
Location: HEL
Programs: AY Platinum, TK Elite, BT Executive, AA, BA, SK, DL, NT, WB + hotels
Posts: 10,260
You can use J check-in and you have lounge access even if you choose to use a non-status card for this reservation. Just present the status card if they request it at check-in or at the lounge.
I am not at all familiar with CX's programme but I would prefer AAdvantage to AY+ for sure.