I've never used much butter when I make it, generally I find that the skin and surrounding fat plus the interior steam created by the beer keep things from drying out. The skin itself will get fairly dry, but it'll lock in a lot of moisture. I usually use some sort of poultry or meat rub, you can use almost anything to suit preference, and I make sure to get the rub under the skin. It takes some care to not tear the skin but with some patience it can be done and it really makes the meat more flavorful. If you're just basting or otherwise seasoning the exterior, you will help prevent moisture loss but you won't really add much flavor unless you care to eat the skin with the chicken (I generally don't). On top of that, if you're basting mid-cook, you could end up doing more harm than good to the final product by opening the oven door/grill cover too often and creating heat fluctuations. Specific to seasonings, chicken can be a palette for so many flavors. If I was to make one right now, I'd probably use (off the top of my head) . . . some garlic, ancho chili powder, black pepper, thyme, maybe ginger.