and the majority of the time, the best answer is just off-camera flash, or bounce flash if the situation is right.
I find that kills the natural lighting of the place, and makes everywhere look "samey" not to mention drawing attention to yourself and distracting the people from what they're engaged in. Flash is an enemy of candid natural photography imho. Most people can't pose well, so I try to blend in and just always be around with my camera doing things. Making bright flashes every now and then can be kind of distracting and not appreciated in a lot of places.
Everybody has their own style, but for myself I find that all my favorite dark reception hall shots are made with a setup along those lines - and honestly, the wide aperture is more of a hazard than a benefit so I find myself at 4.0 as often as not, because things are moving so fast that getting a razor-thin DOF dialed in exactly where you want it is next to impossible. The off-camera lighting provides the drama and subject isolation that you usually rely on bokeh for.
Before I was using the 85mm f/1.4 I was using an 85mm f/1.2 canon. Why did I switch? focus speed. Manual focus on the 1.2 was slow as molasses because it still used the autofocus motor to do it which is notoriously slow. Whereas the 1.4 has real manual focus and a great deal faster autofocus.
That being said, even with super slow focusing f/1.2 with extremely fast moving targets a solid focus is achievable. Prefocusing to a specific plane and waiting for the subjects to come in line with that plane while being in an interesting position.
A tad difficult, but I find almost all of the worthwhile shots are, otherwise they'd be common as mud.