Guinan would of been a good character for voyager however that would of took away from Neelix being Voyager navigator through space and I doubt Kes would of ben needed without Neelix.
On epoint you Didn't tutch on which i really thought you would have would be Guinan-Seven of Nine
relationship as far as Guinan having ahate for the Borg but in the case of I-Borg she saw that he was no longer Borg and actually defended him against Picard. No doubt the process of her being resentful for janeway allowing a Borg to become a member of the crew and to trust her would of been great. Plus the changes through the seasons of Guinan and Seven comming to terms with one another and getting closer.