Once upon a time when I was in my late teens, maybe 20, I found a little lost boy around 5 years old at the Cedar Point Amusement Park in Ohio. To this day, I'm haunted by it. I knew he was lost only by the look of sheer panic on his face. He stood frozen and didn't ask anyone for help. I thought maybe he was told to stand still and wait so I just watched him for awhile but nobody came for him. I finally approached him and asked if he lost his mommy and daddy, to which he nooded yes. I asked him his name and he wouldn't say anything. I asked if he was told not to talk to strangers and he nodded yes. (This was early 90's ish when cell phones weighed a few pounds and few people carried them or I would have asked if he knew their number.) So I explained to him that the people with the name tags worked there and could contact the park's police and we would ask them for help to locate his parents. I told him he didn't have to hold my hand because I understood I was a stranger but he could follow me while I went to ask. A lot of good it did, the employee told ME (the stranger) to take him to the lost and found/police area. So I had her explain that to him and he did follow 2 steps behind me the whole way there. I don't know what happened as I explained the situation to the person in charge who assured me they would handle it, I gave my name which they asked for and then left feeling horrible the whole day. In a way I wish I had stayed but I got the impression that wasn't how they "handle" those types of situations.
So anyway, I'm now the really really paranoid mother of a 2 year old toddler. We took DS to WDW for the first time in June and my DS was harnessed. I didn't care what, if any, dirty looks I would receive,. Fortunately, I found him a cute monkey backpack harness and I got compliments on it rather than dirty looks, but I still don't care what people think (I've also seen negative remarks here on the Disboards). DS will again be harnessed during our September trip and again next May.
I totally agree with LadyZolt about using harnesses for peace of mind, but even with just 1 toddler being looked after by 2 adults and my 12 yr old niece, I won't risk not using it. My DS is the type to run off to characters but even if he wasn't my opinion would be the same becuase people do cut in between you even just walking and it only takes a second to become separated. When my DS is old enough to understand we will do what many have mentioned and will practice. I do not like the "don't talk to strangers" speech for many reasons including that it hindered the little boy I found who was frozen and wouldn't speak because of it.
The bottom line is...until, I am absolutely certain that DS is old enough and mature enough to approach a CM (who thank god have been trained to handle lost children better than the employees at Cedar Point in the early 90's) and convey that he is lost and show them a dog tag or luggage tag or whatever, I won't chance it. I don't know what age that will be but I'm pretty sure he'll still need to be harnessed at age 3. So to the OP, I would ask if your 3 yr old would know what to do with the tags/bracelet if she had them and would she be bold enough to fight the crowds and find a CM to help her if she did, heaven forbid, get lost?
And btw, I like the idea of telling kids to approach a CM working a cash register.
Just my $.02.
, and I am worried about this too. My children are 4 
. I have been telling them about how important it will be to stay with us, etc., and they are usually pretty good about it but I am worried that on their first trip they will just be too excited 
to remember. 
