We hired a responsible college girl to stay in our house. It worked out well. We think we would have had to be too busy tending to the dogs with two aboard.
Now that we have one we take him along. He was 7 when we started and at first he wasn't comfortable, but after a few day sails he got used to the drill and he would get just as excited when he saw the PFD come out as with the leash. He's become a great boat dog. His behavior is so good it's as if he's trying to say "don't leave me at home again".
Dogs are very social and they like to have a "den". I think dogs like the closeness of being aboard with their owners, and especially of hanging out with their owners in the cabin at anchor.