pixieval--you should try using this pattern for a simple nightgown for the summer! It is a dress but it would make a very comfy, loosefitting easy and quick sleeping garment! No pattern needed!!http://www.craftster.org/forum/index.php?topic=345115.0
If you have a limited supply of fabric, I would do the top in one fabric and the bottom in another, and maybe use elastic under the bust? I think if you started with this simple shape, you can adjust it in so many ways! You can make it longer, shorter, change out the straps...go for it and use what you have!