The Lindy Booth choice for Selphie, Kate Beckinsale for Edea and Rachel Leigh Cook for Ellone are all spot on..

Squall - Hayden Christionson (Not sure how ya spell it XD)
Cid - Al Pacino XD or for real- Monica and Ross's father out of friends (whatever his name is)
Seifer - Paul Walker
Quistis - Sienna Miller
Zell - Seth Green (as someone mention earlier)