Here's an example:
I will be going to Vegas in January and almost always fly Alaska..well Alaska fares are about 280 per person RT for non stop....yes I could fly with stops but that still wont get me what Southwest airlines will...which is RT nonstop at $199 per person. So I may be trying Southwest for the first time and the SWA boarding/cattle system.
The other way to save? Book a package! That's why I am such a fan of Expedia..their package deals always seem to save you money!
do your research! :)