I'd love to see more of home life with the Sareks. As much as humans and other aliens respected him, Sarek must have been treated by fellow Vulcans as eccentric to say the least, with his human wife, half human son, adopted human daughter, and his firstborn full-Vulcan so who turned out to rebel against everything their culture stood for.To be precise, they did not speak to each other "as father and son" for eighteen years, which gives us a little wiggle room, if they want to take it.
And, yeah, if we're going to continue to delve in Spock and Michael's complicated family history, I'm not sure how you can ignore the black-sheep older brother entirely.
There's got to be something more in that. Maybe it's the reason he's the roving Ambassador who barely seemed to spend any time on Vulcan.