They were my least favorite part of Bioshock 1 and 2 really. I know I know, the "choice" of fighting them or not...by acceident or by design. Ok I admit that could be kinda cool. However, too many times they accendently were hit and came after me, and when I had no ammo! Plus the Big Daddys were loud and made the floor unrealistically shake real hard when they walked. They distracted the atmosphere. They were cool in the first one, but even by the "new one" in the second one, it was getting old.
I'm hoping in the 3rd, 2k concentrates on a carnival atmosphere plus splicers that can befriend you or at least choose not ot attack you, if you dont attack them. Splicers the smile and ask "what you looking at"? but dont always attack. Splicers can be the key if done right. And good level design trumps everything.
By leaving the BD and LS out of it, that would make the BD/LS thing in the first two Bioshocks more legendary.
Oh, and the big sisters that attacked you, leave them out too. They annoyed me in a big way. B3 can be a chance for 2k to go in a new direction!