The only multiplayer I play is co-op. Not a fan of single player franchises with shoehorned multiplayer elements. I would be in favour of a cheaper standalone single player game with an optional $10-$15 "online pass" multiplayer.
Roll on Borderlands 2
Playing: Borderlands(great co-op,HUGE amount of content),Too Human(better late than never lol),Saints Row 3(Penetrator ftw),Minecraft 360,Harry Potter Lego.
Patiently waiting for: Tomb Raider, Borderlands 2