Not sure what direction a character like Tuvok would go in. He's a Vulcan so not going to have a big angsty time about being lost in the DQ. He's married with children so not going to have any relationship development. He's not a hotshot so not going to have any issues with wanting to do something he's not ready to do. Vulcans are a bit painted into corners unless them make them vulnerable like Spock or T'Pol. The Big Vulcan Storyline is always Pon Farr.
They did do some development with him and Neelix however, good character development for Tuvok to come to grips with his negative emotions and how it was effecting his crew interaction. This theme wasn't a one off ep either so I'd say Neelix and Tuvok were used to good effect as a duo.