Skip-floor elevators. Half the elevators would go to even-numbered floors; the other half to odd. From the ground floor, people could choose expediency (take first available, then use stairs for one floor up/down) or convenience (wait for the preferred elevator). Additionally, elevators should not allow users to select a floor adjacent to their current floor (e.g. can't select floor 2 from lobby).
Employees/Visitors with mobility concerns should be able to use the card swipe in order to over-ride the restrictions.
The convenience of the elevators is currently very wasteful; using the stairs for these short distances is healthier and allows for faster travel via elevators (making less stops), which decreases power use.