The best type of porn to watch with your significant other is anything made by Andrew Blake. It's "classy" hardcore porn that even women who aren't fans of porn can enjoy.
Hidden Obsessions has the hottest girl-girl scene you will ever see and even women who aren't into that will find it sexy. Night Trips I and II and House of Dreams are hot and made classy in a style women will like and men can still enjoy.
His other films are well made too.
I've only joined one porn site and that was
http://www.suicidegirls.com and it was a damn good site. That's primarily a softcore site with a little girl-girl action. Been tempted on several others in all sorts of niches but haven't pulled the trigger.