I have some Polk bookshelf speakers that I want to use for my surrounds. I don't really want to hang them on the wall...but was thinking of framing some "speaker holes" into the walls (which would be drywalled) where the face of the speaker would fit flush against the wall and the speaker body would sit in this framed out "box" in the wall? Walls are not drywalled yet. Will not have columns along walls to hide speakers in. Is this an option? Will this mess my sound up too much?

Yes there is a very good chance it will mess with your sound too much, are those speakers forward ported only?

If its not drywalled yet and you really dont want to hang them why not look into some inwall speakers that are designed for that application. Then they would be flush on the wall

I think you could get away with wall niches as described. You would want to decouple the speakers from the wall by putting something like foam/underpad under the speaker.

yes they are forward ported only. This is why I thought that having them inside a "cubicle" wouldn't matter. Thanks for the advice.