I’ve experienced many time where my party and I have spent more time finding good level dungeons than playing them. There will be 6 of us server hopping and trying to find dungeons (mainly 51 and 52) for sometimes 30 minutes.
I feel that for all main areas (the forest, wastelands, and ice castle) there should be subdivisions with tighter level ranges of portals. This will help the players find the dungeon levels that they want to play, and know the area to go to and find them.
For example, the wastelands can be divided in 3 parts:
Dungeons Lvl 10 - 20 in the first division
Dungeons Lvl 20 - 30 in the second division
Dungeons Lvl 30 - 40 in the third division