Level scaling can always have some bad repercussions.The best way ? Have a HM version of maps, with all monsters being lvl 80, all normal monsters being veterans, all veterans being elite, with rewards being scaled up for lvl 80 players. Every day, a different HM map of all area (krytia, ascalon, shiverpeaks, etc) can be played by peoples, so you'll always find players doing the events, and changing the map every day will break the monotony.