Judging by what I watch - do you think I'll like Nip/Tuck?

Nip Tuck is rather raunchy so don't watch it if you are the more retiring type though judging by what you do like to watch e.g and The City and Six Feet Under that shouldn't be a problem. The best season of Nip Tuck is season 3 when someone is going around slashing the faces of beautiful people (so you might like that as you watch Dexter) You might want to give "Californication" a try as well. And as you like True Blood you may like the shows Moonlight and Supernatural.