While the alcohol in the beer boils off, the flavor it leaves is fantastic. If you insist on non-alcoholic, you have O'Doul's, and if you can find it, Jet near beer. You can also use cola, root beer, ginger ale cider, orange juice, etc. Don't be afraid to experiment. I would highly recommend one of the holders, such as the Bayou Classic Chick Can. Beer can chicken is sometimes called Drunken Chicken, and I don't want falling Down Drunk Chicken
I fixed two Drunken Chickens recently for company, using Bud in the cans, and used a packet of BBQr's Delight Jack Daniel's Old No. 7 pellets, and they absolutely raved about the chicken. Even the white meat was tender and juicy, and rather than looking like it had shriveled, as I have seen with other methods, when I took them off the grill, it looked like the skins were about to split.
Good eatin' and many BBQ's for you.