Hmm, well I guess maybe check with your 17 year old. My kids have never been embarrassed when we called them on the walkie talkie. We had a great time with them. As a matter of fact, this is how we kept each other informed of great bargains in port! Hey mom come check this out....you oughta see this....
Our group cruise intends to use them for everyone, and they do have a silent mode to prevent all the noise when you would rather not hear it. My kids have said our little interruptions have helped them out of a few sticky situations. But, if they said it was embarrassing like MOM said, I wouldn't do it.
Now that they've grown a little we tend to hang out together. Maybe it's a southern thing! This is a senior trip for the kids and I've had lots of them beg to go on shore excursions with me. My 18 year old is planning a party all night contest between the grads and the parents! She swears we will drop first, but I don't think so! They can't wait to video the parents and grads dancing so they can show it to everyone when they get home.
With that said, take all the ideas (and MOM had some good ones! note to self...bring post-it notes), find what works for you and have fun!