With many airlines either announcing checked bag fees, or dramatically increasing existing ones, the cost of checking your bags could exceed the actual cost of your ticket. 

Or in some cases, upgrading to first class might be cheaper than flying coach and then paying to check bags. 

Recently a passenger flying between New Mexico and Los Angeles wanted to check two bags. At United, it would have cost him $100. Then he received an email the night before the flight, giving him the opportunity to upgrade to first class for $97. If he upgraded, his bags would fly free, he’d be in the front cabin and even save a few dollars. Of course it made no logical sense, but it was a no brainer. He upgraded. So look for some of those last minute upgrade offers.