Soundboard
The soundboard is the voice of the instrument.  The bracing controls the basic timbre and the sustain; the choice of material controls responsiveness and quality of that voice.  In each species, the wider the grain is, the boomier the tone.  The narrower the grain is the brighter the sound.

Adirondack Spruce	Sitka Spruce	European or Engleman Spruce	Cedar

Back & Sides
The back and sides flavor the tone of the guitar and add qualities like warmth, richness, brightness, and liveliness.  I have placed them in order of the richest rosewoods to the brightest maples.

Brazilian rosewood	Indian rosewood	Pao Ferro (Bolivian rosewood)	Pear	Koa
Mahogany	Big Leaf Maple	Eastern Hard Maple

Neck wood
The neck wood affects the tone too.  The harder, more dense the neck, the greater is the sustain and the clearer the tone.  A softer and lighter neck wood like mahogany lends fuller overtones  to the sound.  A heavy neck with a light body can throw off the physical balance of the instrument and make the neck sit too heavily in your hand.  Neck woods below are listed lighter to heavier.

Mahogany	Walnut	Big Leaf Maple	Eastern Hard Maple

Bridge
Rosewood and ebony are used for the bridges.  All the sound vibrations are transferred to the top through the bridge, so it is a very important part of the tone chain.  The harder the material is, the better the high overtones are transferred to the soundboard.  Changing the saddle from bone to ebony, say, would warm up or darken the sound.  A rosewood bridge is softer than ebony and would assist the warmth or mellowness of the guitar.   Ebony is harder and tends to help bring out the trebles and produces a clearer and more pure sound.

Rosewood	Ebony