Actually, In my experience I've found rottweilers to be lovely loyal and trustworthy dogs. They have an alarming reputation because their strength has been misused by braindead idiots to train them in unsocial behaviour. They are frequently trained for guarding and other lawful purposes.
Depending on how mobile you are, one of the spaniels seem ideal but exercise must be an consideration. Seeing you already have a grandson, you'll be aware that a dog is not an household item but an everyday commitment.
If long walkies is an issue may I suggest one of the small ankle biters with a good disposition. Make sure you see the parents if possible, some of those small ones are real viscious.