Good questions Joseph.
My rate varies on several factors, some that you mentioned (close friends), but others include:
how far I have to drive increases the rate
which band would I work with, I charge less with folks I know will be easy to work with; and I only do live music for weddings
what are they expecting (duple improper contras versus community longways and circles); managing expectations of dedicated dancers who think their entire extended family will get to heys and contra corners, I'll charge extra for that.
is it an open bar, cash bar, or alcohol free (more alcohol -> higher fee)
The vast majority of weddings I've called haven't run on time; and so I don't charge an hourly rate. I bill a flat fee, on the understanding that I'll be there before they need me, stay late if that's where it's at, and probably only call three dances.
My regular rate ~$400 (I call weddings in VT, MA, and NY); which seems really high if I end up calling only 3 dances. But is also me giving up a Saturday evening. Imagine asking a plumber to be on site from 6 pm to 11 pm on a Saturday.
Close friends, less than that or free.