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.
Data was taken directly from X'on in the Phase II handbook, who was supposed to take Spock's place (Nimoy was unavailable). He was supposed to embrace emotions, because he realized they made Spock so effective. "We'll have humor our of seeing X'on simulate laughter..."
Similarly, Riker and Troi were light rewrites of Decker and Ilia.
Many episodes of TNG season 2 were rewritten from scripts for phase II, due to the writers' strike. It definitely feels the most like TOS out of the rest of TNG.