Hiya Left Of Sam,
Regarding an Adirondack top being too bright...
If built the exact same way (thickness, bracing, etc), it is true that certain top woods will have certain characteristic sounds, but the thickness, bracing pattern, and bracing shape & can be altered to modify the sound of the soundboard. I have heard stories about "blind" tests where listeners were not able to identify the top wood of different guitars. Remember, the top doesn't create the sound - the soundboard does. And the soundboard is the combination of top wood, top bracing, bridge, bridge plate, (& finish). It is this combination that is the sound generator.
The sides and back do 2 main things. First, it is an echo chamber and will color the sound created by the top based upon its reflective properties. Get a porous and softer wood, then the brightness of the echo will be sucked away somewhat (think of a room with lots of curtains in it versus just bare walls and windows). Second, the back can be designed to freely vibrate in sympathy with the top to help create a slightly fuller tone and more sustain. The vibrational properties of woods will change the sympathetic response of the back, again coloring, but not "creating" the sound.
I think sitka is a good choice for a first steel string guitar since the wood is workable & forgiving, and not extreme on either side (stiff or soft). Adirondack spruce should be fine to work with, too, however, so you don't have to over think your decision.
Since the discussion turned to preparation of binding channels, here is a link to some photos of my simple, cheap, and effective attachment I made for my bosch colt router.
https://www.facebook.com/photo.php?f...type=3&theater