Business is much better for long flights. For flights under 5 hours it almost does not make any difference.

BOS to SFO, domestic business is more comfortable but not to the degree I'd likely pay out of my pocket for.

	▲	piperswe a day ago \| parent [-]
		United premium transcontinental business class between SFO and BOS is quite nice and reasonably affordable. It's no Polaris, but they are comfortable lie-flat seats. At least, that was the case when I flew that route in late 2019 - not sure if they still have the same service.