Not a bad set of guidelines, but I think a bit more nuance is worthwhile.

If you only care about price, Southwest isn't a bad choice. But the cost may be in significantly increased travel time. E.g. if you live in the PNW, start with Alaska first, then try Southwest, because Alaska will probably have better direct flight options.

And seat selection... don't bother with it is fine if you're traveling alone. But if you're going on a family trip, this kind of detail is actually important.

Otherwise generally agree. Definitely bring your own food.

Also, if you do fly Alaska, always take your luggage as a carry-on if is plausible. Don't pay up front, because at the gate they'll offer to check it at no charge when the flight is pretty full.