The perfect gift for a son-in-law on Christmas is something that shows you care and appreciate the relationship you have with him. A thoughtful gift that shows you have put some thought into it and know what he likes is always a good choice. Some ideas might include something related to his hobbies or interests, like a new set of golf clubs or a gift certificate to a local restaurant. Alternatively, you could give him a unique and personal gift like a custom engraved watch or a family photo album.