"Thank you for your service."

[DeltaBetaBaby]

I would not initiate a conversation for this purpose, but may add it to an existing conversation. For example, I ride the Metra line that goes from the naval base to downtown, and I get asked for directions a lot when riding on weekends. So, at the end of the conversation, if someone thanks me, I'll respond with "no, thank you" or something like that. I think that acknowledging military service is as good as any other pleasantry with which someone ends a conversation.