I'll echo what others have said - a parlor will have its own sound based on its size - I'm not sure what you mean by a "big full sound" but you should probably play some parlor sized guitars before you make your final decision. The term "parlor" is not all that well defined - some people think that 00 or even 000's are palors - the definintion in the last issue of American Lutherie was "a smallish body but with standard scale length and figherboard width and neck joined to the body at the 12th fret". Parlors also include both the ladder braced guitars of the turn of the century as well as X braced - most have just one tone bar.
Probably the most popular "parlor" plans are by Scott Antes - be cautious that his are drawn as though you were looking at an X-ray of the top (many others are drawn from the back as tho you were looking at the top as you build it). It is very easy to brace the guitar backwards (as a lefty) if you aren't careful (don't ask how I know). Here is a guitar built from those plans along with an OM (the 12 string) and a 000 (the sixer)
The parlor is a wonderful little guitar, but it certainly does not have the big full sound of the larger body sizes - I would call it more of a boxy bluesy sound with punchy mids and trebles, but not terribly strong in the bass. It is amazing loud for a little guitar - everyone says that the Antes plans are over braced and I scalloped this pretty deeply. Good luck with your project.