Tuvok certainly didn't want to become human. He was Vulcan and proud of it. In fact, Seven was borg and proud of it even though she was struggling to re-discover her humanity. I thought the two had a lot in common. In fact, as I think about it further Tuvok would have made a better mentor for Seven than the Doctor because he has a very logical approach that Seven seemed to appreciate yet at the same time had been an observer of humanity for quite a while.
Well, the entire idea of the Doctor being Seven's mentor *was* that it was the blind leading the blind. He was supposed to be ill-equipped for the task--and not realize exactly how ill-equipped he was.