Besides episodes in general, I think it would've been interesting to see Data just in general on the show: An other-worldly character like Spock, yet much more innocent.
I think Kirk would've been won over (as Riker was) the moment Data candidly said "I
am superior in many ways, but I would gladly give them up to be human." McCoy might be a bit more skeptical of this walking, talking machine, yet soon grow to like him more than he tended to admit.
(And if anyone thinks they're clever enough to make a joke that Kirk would just cause him to self-destruct, don't bother.
)