After some thoughts and discussions wtih the crew on my last...
1. Lighting - and I don't mean those who prefer all the storm lts on so that nothing can be seen out the windows. The dome lights on the Boeings are very effective at night turned up about half-way; they provide area cockpit lighting but leave windshield reflections and blanking to a minimum - several of the storm-lt crowd have been converted. Good chart lighting is imperative for tired old eyes, also.
2. Noise. Agree that the 747 was bloody noisy; in addition, resting in the bunk with four Rollers out-of-sync rattled the trim...the newer Boeings have very smooth airflow around the front end, and are amazingly quiet. Pack rumble on the L-1011 was an issue, I remember - 411a weren't those under the flightdeck? The rumble was the louvres not quite positioned correctly....(it's been a long time!).
3. Dryness. Not much you can do here....soak a few towels and leave them out.....I used to fly with some Canadians who flew the Argus, which was capable of 20+ hours aloft un-refuelled. They used to wear wet towels on their heads to combat fatigue - swore it worked...hmmmm. Humidifiers reduce eye fatigue massively.
4. Displays. The new LCD displays on the 777 are much less tiring to look at in low-light conditions that the old flicker-specials.
5. Comm fit. There is no doubt that FANS etc brought about a sea-change in radio usage. No longer any need to listen to a racket over Asia if you can't get a selcal HF if you manage a Logon. Used to happen a great deal; you'd end-up with the speaker on low so as not to miss a call, and the static and gabble was not the freshest thing for the mind...
And then of course there's other stuff such as having an FE to be the entertainment director - I always used to feel that 3 crew were more alert than 2-at-a-time (agree with 411a on this). Legroom etc - agree that the MD-80 is the most god-awful flightdeck for comfort AND ergonomics, and the window seals frequently squealed.
I'm still a big believer that the Cabin Crew should check-in frequently with the Flt Deck, especially as we're locked behind the door now.....