I've been putting the kids' names and our contact information on dogtags and hanging then around the kids necks. It's near impossible to bang up embossed steel tags to the point where they're illegible. Tag-Z was the company I ordered from IIRC.

As far as dayhiking goes: backpacks with water bottle, munchies, jacket, whistle, light, and sunscreen. Sunhat on head, sunglasses on lanyard. I'll add an all weather blanket or poncho as they get older.