Would you like to see a new dungeon in the game? Maybe one in a HoT or PoF map? They haven't added any dungeons since the game was released (at least no permanent ones). The only persistent change to dungeons has been the addition of the Aetherblade path in Twilight Arbor (which is way too difficult IMO). I personally would love to see a new dungeon added to the game, especially in one of the expansions. Maybe even require glider or bouncy mushroom usage for a HoT dungeon or mount usage for a PoF dungeon.
EDIT: I would also like to hear your ideas for new dungeons, raids, fractals, or strikes. What do you want to see?