Whilst all I ever include on the outside of a suitcase is a QTag with FirstName and mobile number (in international +61 format), this proved to be of no help when one of our bags went astray at DFW earlier this year.
Short version of a long story: arrived at DFW from SYD just fine, collected luggage, then checked through to JFK. We didn't notice that 1 bag got 2 tags and another got none.
Untagged bag had a QTag with contact # and was locked with a TSA compliant lock.
When finally reunited with the bag, the zip mechanism had been destroyed (by TSA apparently) to gain access to the contents of the bag - the TSA compliant lock was nowhere to be seen. Additionally, we were informed that it was "not policy" for international phone numbers to be rung in this circumstance.
Still waiting for our compensation claim to be processed by AA...
(I still, however, only include the above bare minimum details on the outside of checked luggage.)