I've always been cautious about opening stuff I collect. I grew up with my father being a Star Wars collector, which would shock people like my oldest friends when they saw his "Star Wars" room because he didn't look the nerdy collector type at all, in fact he's been a back-hoe operator for almost 40 years and still plays base-ball, retired from hockey. Anyway, more of his stuff isn't opened than is opened, and as I grew up I started to follow that example.
Some notable things I can think of that I've never opened is my NECA Alien (Giger) standing over 9" tall and a MacFarlane Queen alien. As well as a Star Wars Unleashed Boba Fett, 300th figure Boba Fett, and a Star Wars 2003 Convection Figure Boba Fett (all silver and shiny).
One notable figure I have opened though is my NECA Alien (Giger) that is 18" tall.