[Cyber Shaman]

I was immensely excited about PSU when we first got that flash animation, back in who-knows-when but after actually playing the game, I just finished PSU on my PS2 once and never came back to it.

I kept an eye on the games and expansions that followed but never played them.

Bottom line, though: What was the story in PSU? I mean, we get to play as Ethan who goes on adventures after joining the Guardians during the SEED invasion, then there're Illuminus shenanigans, and years later some girl goes to find new planets on a ship that looks like a cross between a bird and a magical ferris wheel ... that's it?

[Noblewine]

The story was the guardian colony, Moatoob and Neudaiz are under attack by a unknown race called the seed and you decide to fight them as a Guardian. You later learn Dark Falz has resurfaced and produced those seeds and needs to be defeated to stop his threat on the Gurhal system.

The story was basically a portion of other ideas from the Sega Genesis Phantasy star games. I learned while playing PSU network mode.

girl goes to find new planets on a ship that looks like a cross between a bird and a magical ferris wheel

That's emilia. PSP2 is a continution of where PSU and PSP1 (Vivienne story ends). She lives on Clad 6 working for a Mercanary group called Little Wings.
The planets your mentioned are probably the new maps added to the game. The jungle on Moatoob is a cameo to the Jungle in PSO ep2.
Sega has in-game hints about the ancients and cross-overs but its just for fanbase purposes so it sorta ruins it for people who are trying to make a timeline out of the games. PSP2 hints about the ancient like it did back in PSU but apparently their are forces worse than Dark Falz in PSP2 story.

Sorry, I tried to put a spoiler tag on the vital stuff but I don't know how.