Aircraft type also comes into play.
When it's a long flight (such as HNL to DFW) followed by a shorter flight, the long flight is on a wide-body aircraft such as a Boeing 767, typically with 2+3+2 seating in economy.
Most flights between Hawaii and the mainland Pacific coast are on narrow-body aircraft (such a over-water versions of the Boeing 737 and Boeing 757), typically with 3+3 seating in economy.
I vote for a long flight and a short flight. When flying back to the mainland, the long flight will be overnight. It's long enough to provide a chance to get some sleep. And the 2+3+2 seating provides better options for families to sit together without a stranger right next to you.
In first class, it can make an even more difference. For example, on American Airlines, the first class cabin on narrow-body aircraft has typical domestic first class seating, with somewhat wider seats and more legroom than economy. Nice, but still hard to sleep. The wide-body aircraft, on the other hand, have first class rows that are much further apart, with seats that flatten to 180 degrees for sleeping.