Unlimited access to ClubAcela®, Amtrak's Metropolitan LoungeSM, First class lounges and United Club lounges.
Can an Amtrak Select Plus/Executive member enter an Amtrak lounge at any time, even if he or she does not have a train ticket?
Unlike airport lounges, Amtrak lounges are outside the security perimeter; therefore, any ticket checks would need to happen at the lounge entry desk. The rules say "unlimited access," which suggests to me that they can be accessed at any time.
United Club Members also have free access to Amtrak lounges, but might be subject to different rules. I am specifically interested in travelers with Amtrak status, but others might be interested in whether answers apply to United Club members, too.