I'm a little bit of a knife aficionado. Swiss Army Knives are fine (I carry a Victorinox Huntsman every day), even locking ones.
Why do I carry one every day? Swiss Army Knives are extremely useful. I actually use the scissors in my SAK more than any other tool, although I have used the screwdriver and blade on occasion too, as well as the toothpick. Nice to have around just in case. My mom got her ATM card stuck in the wrong slot on the machine once, and some guy used the blade on his SAK and a Band-aid to extricate the card. My brother, who witnessed it, was awestruck. He carries a SwissCard everywhere now.
It's entirely up to an officer's discretion. If you're carrying a 13.5" long double-edged dagger, then you might just have issues if you're stopped. As long as the knife is reasonable, you're ok. I take a machete out into the woods when I'm hiking and it's never been an issue. Then again, I've never been stopped with it. Tactical/fighting knives are more of an issue.
Definitely avoid any kind of automatic knife/balisong/push dagger. They are all illegal to possess, whether you're at home or not.