It would be amazing if some sort of marker was added to see at a glance if you completed a certain zone kind of like how guild wars 1 was with HM vanquisher.
Another map related suggestion i have is have jumping puzzles part of the requirements for zone completion and show how many a zone has on the map along with the other info like how many waypoints and vistas.
Yet another map suggestion is allow us to click a zones name and see what we have completed in that zone. So say i am in lions arch and want to know which zone/s i am close to completing i could easily click the zone name and it will show that zones completion stats rather than having to pay a fee to waypoint to all the zones to find out how much i have done there.