Fabric ideas for a really nice nightie?

[looseleaf]

This is a long shot and I don't think will make Chat of the Day!!
I really want to make a beautiful nightie for my grandmother who is amazing and she's into sewing and needs a new one.

Does anyone have recommendations of a fabric that's really thick/ soft/ lovely for whatever reason?

I thought of googling brushed cotton but maybe need something with a bit more give?

I don't even know how much I'd need (she's a size 18 as I secretly looked when hanging her old thin one out to dry)

Thank you

Silk makes amazing night clothes - it's soft and it's warm. I'd guess about 3.5 yards?

Oh thank you! I never thought of that. Perhaps I should look at some in a fabrics shop so I get a better idea

bamboo is also really nice

Would second the silk as its beautiful, but liberty cotton is also very nice. Otherwise see what you can get in 100% cotton especially if it says made in Japan