Nothing big happened in Sevii Islands as far as main plot goes, though; Bill had taken you there once to show something, and that was all, sadly. :( This time around, it'd be great if it were different, and both regions plays an equal amount of role.
That would be nice! Though, traveling between regions again would be pretty darn sweet, too. Unlike GSC and HGSS, maybe they could incorporate both regions into the main story this time around? That way, I could imagine it to last a little longer than usual.