If I or anyone else had to chose an essential item it would be a dress. Maybe even the famous LBD. But I think that a single dress that fits everyone('s taste)just doesn't exist. So I would love to have a pattern for a simple and fitted dress which I can adapt to my body and taste.

You could use different pattern parts for the top and for the skirt depending on your size.
Or you can replace the bottom for your favourite skirt pattern change the length of the skirt and the sleeves or leave them out use different fabrics for the top and the skirt.
You could even make a cutout at the back.

Fabric suggestion: stretchy fabric for all fitting parts.