I'd be interested in knowing what Guinan was up to during Kirk's early TOS time. If she's studying humans way back in the 19th century, then surely she'd be keeping tabs on them throughout. Maybe she even knows who Khan is from personal experience of having witnessed his indigenous time
It might have been pretty cool if she'd been around during Zefram Cochrane's warp flight/ 1st contact time too, & Picard finds himself face to face with her again. I never really cared for the Lilly storyline anyhow. Alfre Woodard is very good in it, but the character never really resonated with me, any more than say Lillian from The Voyage Home. Just another local being polluted by time travelers
Whereas, running across Guinan again would be very interesting, especially in the capacity of having to reign in Picard's whale hunt. The irony could be that this would be before her people got wiped out by the Borg themselves, & in an odd creepy way, Picard could be why she survives it, because she knows about them from encountering Picard 230 years earlier, completing a strange cycle where Guinan is the first person Picard meets who knows about the Borg, & at another time, Picard is the first person Guinan meets who knows about the Borg
