Urgarde Keep, Old Kingdom, Drak'tharon Keep, Gundrak are alright instances .. the ones that were best - exp wise - Drak'tharon Keep being the worst. Gundrak being the best, WITHOUT a doubt.

The Nexus is alright, just some fucked up trash mobs. Azjol-Nerub is alright, but there's no trash loot (!) and quite alot of downtime aswell.

I levelled 70-80 in instances, did only 2 quest outside instances.