I have a wonderful enormous doggie. I live alone and he does fine with 8-12 hour days. When he was a puppy, I had a walker come get him 2 times a day, but now that he is ancient, like 5 yrs...no problems.
Agree with everyone else, Do not purchase animals from pet stores. Get a sweet one, or two cats at the shelter. the reason you might want 2 is that they will keep each other company when you are gone, as long as they like each other. Every spring, shelters are inundated with kittens, might be time to go pick out 2 littermates.... My next dog is going to be a cat.