For your application I would suggest Poplar since it paints well and machines well.
Now your choice is mortise and tenon or rail and style.
Mortises can be difficult without a dedicated mortising machine.
A router can be used but will not make through mortises in 3" wide stock easily.
Half laps can be used with good results when pinned.
A variation could be a plywood panel set in a dado all around then rails added on either side to give the appearance of a raised panel trimmed with moldings.
Another variation would be a barn door look with edge glued boards and a set in diagonal for bracing.
So, what "style" do you intend to make based on the look?
Raised panels? Flat panels? added molding inside for more decoration? Arts and Crafts or Mission style?
The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
Last edited by woodnthings; 01-21-2012 at 07:47 PM.