This is a idea I've used several times in the Restaurant.

It's a simple baste that works wonders on chicken.

1 lb. Unsalted butter
1 bottle of American style Ale. (Firestone works the best)
1 Cup Dried Rosemary (Crushed)
1/2 Cup Dry Rub

Melt Butter, Add Beer, Add the Rosemary, Add the Rub

I split the chicken at the breast and leave the backbone and ribs in place (basically your cooking a whole chicken but without halving it.)

Season the chicken with the same rub you used in the baste. you might want to season again halfway through the grilling process as the baste tends to take most of the rub off.

Start your basting about half way through the grilling process, every time you flip.

I use wood or charcoal. I try to avoid gas grills as the flare up is pretty bad

Enjoy!