I know you say the boxer is a gentle giant now..is she the only dog now? Do you know the background of the boxer from the humane society such as what type of situation she was in before. You just want to be sure it will be okay being around other dogs, especially ones smaller, since she was a HS dog and some of them come from bad experiences, etc.
I think the Yorkie is a cutie. Go see her in person and see what you think. Also, be sure you are comfortable with the breeder, don't just go for inexpensiveness (not saying you can't find an excellent breeder & get a great dog for a great price!).
Good Luck!
