How can I cook more flavorful Chicken through and through?
One option to consider to add flavour to a chicken is brining. I've personally never brined a chicken, but everytime I come across mention of it in a foodie blog, forum or elsewhere, it always seems to be considered a good way to impart additional flavour into the meat.

Since writing this answer I've followed Nigella Lawson's recipe for Spiced and Superjuicy Roast Turkey which has resulted in fantastically tasty and moist turkey at Christmas every year, to the point where I won't countenance turkey at Christmas without brining it now. If this translates as well to chicken (which I fully admit I should've tried by now!) then it's well worth the time and effort.