I'm not sure how I feel about including an address label with a gift. Particularly for say wedding/shower gifts. If they had your address to send you an invitation, they know your address.
I will say, I very much appreciate the handwritten thank you notes I have received. While, yes, the practice started because pen/paper were the only/primary methods of communication, I think it's a tradition/courtesy that should be continued. Depending on the 'gift'. If I pick up a doodad for someone I know simply because I think they will like/use it I don't expect a written thank you. If I make a quilt/other handmade gift or some other substantial (wedding) gift, I think it's appropriate for the recipient to take the time to write a thank you note.