I wanted to book SFO to IAH recently. Friday afternoon. Non stops are $686. Connecting flights run about $260. Frontier looks to be the only competition on nonstops and they charge $169. Usually I find that connecting flight fares are higher than nonstops but not with this city pair.

I ended up booking through DFW for $259 but hope to do a 'day of' flight change to a nonstop for the $75 fee.