First, let me tell you that you have great looking plants and many of us would of die for the such beauties. :-)

Re: Nikko.
Since you don't care about next year blooms you could simply cut whenever and whatever you think is appropriate.
If it would be me, I would of left everything 'as is' till spring and then would of prune whatever ma-nature left unpruned.
Also, it seems like your Nikko hedge has a lot of dead canes from the previous years and in need of cosmetic cleaning. You should cut them down to the stub and remove completely. While this could be done in a spring as well, I would of rather do it in a fall, when foliage fall down.
The only reason for that is that in a fall you'll be able to clearly see what is the old dead wood and what is not. In a spring completely dead and not dead, but just dormant yet, canes may look very similar for untrained eye.
Re: PG.
Basically answer is the same as above with only difference that while at the pruning task I would of try to save as many vertical shoots as I could. To prevent snow breakage you may want to remove flowerheads in a fall.

Thank you very much for your advice. I will go out there this afternoon and clean up a bit. It is amazing how things go haywire with one season of maintanence missed.(not that I really knew what I was doing in the first place)

Is there a forum for butterfly bushes? Those are taller than me too....

No, there is no special forum for buddleias exist, but rules for them in z5-6 are fairly simple: cut everything down to 6-12" in early spring. That's it. They'll grow back in no time.
Good luck.