as for world mysteries.. I need the last one from: Strange Cultists, The Demonic Threat, Seals of Power, The Grand Experiment and the Art of Creation.
All those are former endgame raid instances.
Strange Cultists, The Demonic Threat - Gorluxors's Tower in Yazes (4x lev).
Seals of Power
- Dead City in Cradle (50 lev).
The Grand Experiment - Tep's Pyramid in Irdrich (55 lev).
Art of Creation - Eclipse in Umoir (60 lev).
Because you have overleveled raids you could join (though it is next to impossible to find one until you get 65) there won't be exp from them.
Squirrel or some spot with nice quick resp of mobs (like haregons with "Haregons" quest active) and grinding...