Mine wear collars 24/7. If you start young they get used to them. They go outside to potty so they are outside a lot. They are chipped but a neighbor would be most likely to find them if they slipped away. I'd rather they call us right away than have to take them to a vet to read their microchip. Most non-dog people have never heard of a chip and would never think to do that. Their tags clearly have their name, our phone number, "Microchipped" and "Needs Meds". Loki has our address on his tag but his tag is bigger. I like this tag the best!
http://www.boomerangtags.com/store/list.php?A=S&ID=25
A Yorkie got lost in our neighborhood a few weeks ago and someone found her and stopped by to ask if she was ours. She had no ID. Luckily we knew there was a family a few houses down that had a Yorkie too, but the guy who found her had no idea!