Am I just not a dog person? Fostering a dog?

I've worked as a dog groomer and volunteered at our local shelter working with dogs. I adore dogs of many breeds and always enjoyed time spent with them. My sister is trying to re-home her mini schnauzer due to asthma attacks so we agreed to foster him for four months to give her time to find the perfect home. I was excited to take this opportunity. If the dog worked well in our household we were planning on adopting him ourselves.

I'm sad because I don't feel I am bonding with him at all. We go on daily walks, we've been hiking a couple times, and he is a very well-trained little dog. He's run away from home twice when a friend left the door open but he came right back at the call of his name. I'm starting to wonder if I like the idea of having a dog more than actually having one. We have many other pets and I spend an entire day a week cleaning cages so I'm no stranger to the responsibilities in owning critters. I don't feel like the extra time caring for him is putting me off. But even though my guinea pigs are bewildered and emotionless I find more comfort in snuggling them than I do the dog.

Dog owners- have you found that different breeds/personalities of dogs suit different people or am I just not a dog person?