Another granny undie "fan" here. Over 2 years on and I still haven't gone back
As for clothes, DS was a winter baby, so had some yoga pants, stretchy PJ bottoms, t shirts and a couple of cardy's as my wardrobe, and took my soft robe to keep warm during night feeds. All very soft and comfy
Will be pretty much taking the same things for DD's birth in a few weeks
ETA, throw some socks in too incase your feet get cold.