Regarding How do I get access to the Continental Presidents Club?, there is one access method missing, which is CO's agreement with Amtrak for ClubAcela.

Anyone who has obtained Select Plus Status in the Amtrak Guest Rewards Program automatically has ClubAcela access, and it is printed on the membership card that is mailed out when the status is obtained. Showing the card at a CO President's Club will allow the member +1 guest into the CO President's Club Lounge. Same day tickets on CO are NOT required for access using the Select Plus / Club Acela Card.

Amtrak's description of the Select Plus program here confirms the access.

As a side note, "Continental Airlines President’s Club members with a valid membership card or a Continental Business First ticket for same-day travel are welcome at the New York ClubAcela."