Sophie wears a pink suede one with a "diamond"
heart in the center. Now I have so many id tags on her AKC, Chip id, Rabies Tag, plus a beautiful dogbone shaped id with crystals
on one side & my cell phone number & the word "reward" on the other, that it is getting kind of grungy looking. I am so paranoid about her getting lost that I make her wear them all day, but they come off only if she is in her crate. Everyone thinks I'm over doing it, but after you have read a few stories about them skipping out the door or whatever you don't want to take the chance.
That being said, harness for walks or fastened in her "puppy purse".