[The.Knitter]

You could use the "Gramma's Favourite Dishcloth" pattern, if you don't want anything fancy. This is just plain garter stitch.

I would use a chunky weight yarn and a size US 13 needles (I'd probably use a 24" circular needle for this project).

Cast on 4 stitches.
* Knit 2 stitches, yo, knit to end of row.*
Repeat this * row until you reach the desired length of your blanket.
Next row: K1, **K2tog, yo** repeat from ** to ** until you come to the last stitch, K1.
Knit across three rows and then bind off.

This will give you a blanket that is narrow at the top, gets wider with each row you knit and is very wide at the bottom; is easy to make; and will be nice and warm. It will have small holes down each side of the blanket and across the bottom to dress up the plain stitch a tiny bit. You can roll the top down a bit to create a collar when you are wrapping yourself up in it.

Good luck!