Alternate dialogue, yeaaaaaah!
Friend Ash stuff (which I did *not* thoroughly test so I'm not sure what triggers the difference between her calling Shepard "Shepard" or "Commander" at the end of the conversation):
Regardless of poetry: If Shepard doesn't ask Ash all of the questions (or maybe it's one specific one that triggers the change), she'll say "Will do, Commander" when Shep leaves. Asking all of the questions results in "You too, Shepard" (in response to Shepard's "I should get back to it. Take care of yourself.")
Not bringing her poetry (although it maaay also be caused by going Renegade once on Mars) and asking Ash why Shep didn't hear from her:
Ash: I couldn't face you. Even when Anderson requested my presence, it was....difficult.
Shepard: It's okay. We're both professionals. We have more important things to worry about.
Ash: You're right. I'm just restless, laying here, doing nothing.
And of course loyal Shep gets the grand "It's always been you" speech to romanced Ash and that whole part of the conversation is basically fabulous.