Just a few things from my experience, to be taken very much as IMHO, YMMV etc.
I've found Mass Hypnosis to be very useful in the late game, even in teams with many AoEs, for two reasons.
It is very good for locking down adjacent groups which threaten to join an already hectic fight; if they do join they'll join later, and if they weren't going to it doesn't matter, as Mass Hypnosis doesn't aggro them.
The other use I found for it was in blaster(or defender)-heavy nuking teams. Mass Hypnosis gives time for them to set up for the nuke, and gives you relative safety to go with them and Fulcrum Shift for them (which does not wake the mobs).
As for Telekinesis, I presonally love the power, but it is tricky to use, and a complete end hog. I would strongly advise waiting until post-Stamina and SOs before picking it up. Once you do however, I have found Repel to be quite useful for knocking mobs into the TK field. TK is most useful for stacking magnitude on multiple bosses at once without needing to hit, and Repel is also auto-hit; this gives quite a nice way to position and lock down bosses using TK, Dominate and Repel. A word of warning though: Repel is an utter aggro-magnet, as is TK. You *will* attract a lot of attention using both.
Just my .02c
