Hm, funny point about the lets-take-Tegan-home thing... though yeah, I wouldn't call it a narrative either - more like a purpose for the character, like for Ian and Barbara in the first two seasons.
And Leisure Hive
effectively ends the random travels that the Doctor went through because of the Black Guardian and the Randomizer, and as such its the beginning of a a new chapter for the Doc - one that eventually made up for the subtlest, most RTD-esque arc in OldWho. And thats one thing I really like about that series. Though technically you're right, series-wise it started that arc, like Rose
started the Bad Wolf arc even though there's not a single mention of it there (it actually starts appearing in the next story).
As for the Ace thing... thats not really a season-long arc, is it? Its an arc that spans through Ace's time with the Doctor, in a similar way as how series 1-7 form a Post-Time War arc for the Doctor, ending with the 50th anniversary special that revises that story for him again. Still, its not without merit, all things said and done... I always thought Ace was the proto-NuWho companion, in both attitude and the way she handled herself in action.