I tend to wear nickers and a long tshirt. Though often the T is replaced by a cami, which is slightly more supportive of the girls at the size they are.
Sometimes PJ's if it is cold.
If I am with my lover I end up just going topless in nickers. I get too hot otherwise (and what could be better than waking next to a naked girl??

).
Planning on getting a short nighty though, something cute that fits snug just under the bust.
After surgery I will have to see. At first I think underwear will be needed, otherwise the covers will get messy. But later, maybe nothing under at all, especially if wearing a nighty or a long T.