A lot of people have already said many of the ones I would love to see (Sanju, Watcher 1, Praven).
For me I would have loved as a Smuggler to invite one or both of the Teraan siblings especially Lenn. I thought Lenn's interactions with the female smuggler were adorable. I would have liked to explore the dynamic of a roughhouse, streetwise Smuggler showing Lenn the "real" galaxy and then on the flipside him also showing her the softer, romantic high-life side he was accustomed to, an opposites attract sort of thing. His sister always seemed more into the politics anyway so she can stay behind and deal with the fallout and my lady Smuggler will take Lenn away.
Also I've said it before but I'll say it again, that one [flirt] with Talos on Hoth was such a huge tease, my Lady SI has never given up that romance hope, they're such a good nerdy, archeological obsessed match made in heaven!