[ultimatemegax]

So here's a little summary of what happens character by character in the different "routes":

Spoiler for alpha:

Haruhi - Flirts with Kyon and perhaps begins the process of going to the same university?
Kyon - Flirts with Haruhi and has doubts about Yasumi
Mikuru - Thinks Yasumi is *ADORABLE*! (umx comment - Seriously, expect some yuri doujins from this couple)
ITDE Interfaces - Nothing
Koizumi - Advises Kyon and has meaningless conversations
Yasumi - The expected new member? Takes guidance from Kyon and integrates the routes
Sasaki/others - Not seen

Spoiler for beta:

Haruhi - Takes care of Yuki
Kyon - Is ordered to hand over Haruhi's power to the Sasaki side
Yuki - Has the "cold" due to contact from the Sky Canopy Domain
Koizumi - Advises Kyon, but finally shows his true character
Sasaki - Doesn't want to go along with the others' request. Seems to be infatuated with Kyon. Declares that she wants to change the world with Kyon.
Kyouko - Apologizes from beginning to end. Appears to be no threat
Fujiwara - Acquires a "regulated item". Very "bad guy"ish
Kuyou - Wants to know more about humans but had a bad experience
Asakura - Encounters Kuyou (preview) and that's it
Yasumi - Appears briefly

Spoiler for end part:

Integrated Route
Haruhi - Runs from being killed by Fujiwara. Also continues plans for university with Kyon
Kyon - Is absolutely useless. Goes to Haruhi's rescue, but can't do anything. Later appears to begin plans for university with Haruhi.
Yasumi - Uses Haruhi's power to mend the universes
Koizumi - "Don't look down on this time period's people!" and challenges Fujiwara
ITDE interfaces - Silently supporting everyone
Mikuru (big) - Affirms that regulated items are regulated
Fujiwara - "Mikuru-oneechan!"; Is in a rush, so tries to kill Haruhi but that ends up poorly.
Kuyou - Is the mastermind behind Fujiwara's plots
Sasaki/Kyouko - Don't appear

And a confirmation of something I speculated earlier:

Spoiler:

Fujiwara calls Mikuru his older sister. Mikuru (big) states specifically "I do not have a younger brother."