With a ret pally your biggest priority after hitting 1000+ res is +STR for damage. Paladins get 2 (2.3 ap with the Divine Strength talent) attack power per point of STR which equals more damage which equals more pwning. But Ret Pallys are much more than the face bashing blunt heroics of warriors, they are very much a support member of any pvp battle with their hands to help teammates move freely and without harm. So therefore your choice to maximize survivability is a viable one when it comes to your gems. But as far as red sockets go, YES!, always put in +STR and all the other gem sockets are your choice. I went with +Crit, +STR, and +Stam gems for the most part because I love to be in the middle of the fray slaughtering my enemies. But as far as resilience goes once you hit 1000 its no longer a necessary stat as far as gemming and enchants.
~ Tanking is a mixture of strength, finesse, and the ability to make up for other peoples short-comings.