H/T The Points guy, which has a great comparison of "basic economy" options to each other and to the "ultra-low-cost-carriers".
I'll have more on this later, but for now the thing I wanted to note was TPG's comment about families:
3. Avoid them when traveling with families, for now — When traveling with small children, there doesn’t seem to be any accommodation to have adjoining seats on United, even if you want to pay extra. It’s unclear what action, if any United would take if a toddler was assigned seats apart from his or her parents.
As Disney travelers, we want to save money, but we need to be careful where we cut costs. This wasn't a point I'd considered much in previous posts on choosing carriers, but I'll update the content to reflect it (and include it in the upcoming post).