Building a king bed frame (platform bed) out of wood?

I am going to build a platform bed for our king mattress out of wood. I could us a little advice...I want to build a rectangle frame and recess the slats so that the mattress sits inside the outer rails. Anybody have plans for a frame like that? If not, what wood should i use so it stays as light as possible and will look decent? Any and all info is appreciated. A king bed is 76"wide x 80" long. Thanks.