Boarding by Elite tier would be nice, but to me, the only advantage to boarding early is the bin space, and unless there truly are 100 elites in one flight, this should not be a concern.
Anyways, one thing I never understood why it hasn't been done before, is why not hand out a little piece of paper (or double the size of the contract of carriage slip that gets stapled to the boarding passes) with carton like drawings (
similar to the safety cards), to teach people how to board more efficiently and faster?
Most casual travelers do not know that the best way to stow luggage is wheels out. Also, most people forget you can use the space under the seat in front of you only temporarily, then move it behind your feet after take off. It could also illustrate about putting winter coats and the like on top of bags after they have been put away.
By the time they hear the announcement about not taking up overhead space with coats, it is usually too late.
I think some good creative drawings, even perhaps adding some humor, could do wonders, at very little cost.
Ikea does this very well:
