There's really no safe way to check bags except perhaps to "gate check" them, at the boarding gate. You can do that with some airlines and some items, i.e. they do this for baby strollers and excess carry-on bags.
You can secure a Pelican case with padlocks, but unless you use "TSA Safe" padlocks, the TSA cuts these off. And the "TSA Safe" key sets are available cheap and easy to anyone. The TSA also fires about 500 agents for pilfering baggage every year. So personally? I'll use colored zip-ties, knowing the TSA can easily cut them off, but I can easily tell if there's been tampering. And replacement zip-ties tucked down inside the bag. And, sadly, buy baggage insurance if you don't have enough with your "contract of passage" or credit card purchase.
Checked bags? Roll the dice in Vegas. Some of the airlines, like Delta, actually tell whoppers of lies about when and how the bags themselves will travel. DO put your contact information inside the bag, so if you get separated, they can't say "We didn't know whose bag it was."
