I would strongly discourage you from doing textured walls.

I would leave ceilings smoothe. I like orange peel tho!

I think it will be more cohesive if the walls and the ceiling are the same texture. There are different levels of orange peel ranging from fine to heavy. I would only consider a flat ceiling if you had molding to separate the walls and the ceiling.

I must agree with he above comments, I would keep the walls smooth.